Background: I own the DJI Goggles, P4Pro and P4 and all have been updated to the latest firmware versions available as of the date of this post.  I have been flying DJI aircraft for over 2 years and have over 7 million feet and 86 hours of flight experience.

What I like about the DJI Goggles:
1) DJI Goggles LCD image is bright and clear, especially when the Goggles are connected to the HDMI port on a P4 or P4Pro equipped with an HDMI module. The apparent resolution of the live video image displayed in the Goggles is acceptable (720P), relatively non-pixelated, and refreshes quickly when flying with the Goggles connected to P4/P4Pro RC HDMI port and, especially when flying the P4Pro in 5.8 GHz Auto HD mode, which yields the highest quality live video image with the P4Pro at distances up to several miles from the RC.
2) Goggles are well-designed and balance well on the head with the battery weight in the back of the head band counterbalancing the weight of the large Goggles element in the front. The padding on the DJI Goggles headband is high quality, generous and feels very comfortable. The ability to adjust the head band size for a comfortable, custom fit using a wheel on the top or bottom of the head band works extremely well and can be quickly changed for another user.
3) The ability to flip the Goggles up with one hand to be able to check your tablet (when flying in HDMI connection mode) or to do any work requiring a view of your surroundings is a very useful (can't live without it) feature. Unfortunately, flipping the Goggles back down over your eyes is a two-handed operation with one hand pulling the Goggles down and the other hand holding on to the headband in the back.
4) Both Head Tracking Gimbal and Head Tracking Flight modes work with my P4Pro (but note comments below).
5) Head Tracking Gimbal mode works with my P4, but Head Tracking Flight mode does NOT currently work with my P4. This has been confirmed by at least two other P4 owners on these forums.
6) The built-in DJI GO flight app and touch pad interface are well thought out and together these features mean you are getting a touch-interface mobile device and superior Goggles for a relatively cheap price of US$450. However, you will need to spend several hours getting familiar with how to navigate intelligently through the flight app menus using the touchpad menu system and to gain familiarity with where all the camera options, HDMI connection options, Record Stop/Start, Auto Take-off, Camera Focus, etc. features are located.
7) Battery life of the DJI Goggles is more than acceptable - good for several hours of flying time.
8) DJI includes both a right-angle full-size to micro HDMI cable and a full-size to mini USB cable in the box. You will need an adapter to connect the HDMI cable to the mini HDMI port on the DJI HDMI module accessory add-on for the P4/P4Pro RC. The supplied USB cable can be connected directly from the DJI Goggles to the full-size USB port on the P4/P4Pro RC (with or without an HDMI module accessory).
9) It is possible to Focus the P4Pro camera using the "Function" button on the bottom of the Goggles to display the focus cursor, then move your head around to adjust the focus point, and then tapping the touchpad to focus camera lens at the desired point on the screeen. It is CRITICAL that you learn to do this at the beginning of (and during) every flight because it is not easy to determine if the image is properly focused just by looking at the live video image displayed on the Goggles. I strongly suggest you activate Continuous AutoFocus option with the RC connected to your tablet as I have not found this feature ON/OFF switch in the Goggles menus.

What Could be Improved / Better Implemented to Improve User Experience with DJI Goggles:
1) I find that, currently, Head Tracking Gimbal and Head Tracking Flight modes are only a gimmick - something fun to try maybe once or twice. Head Tracking Gimbal mode can also be entertaining for a friend to wear the Goggles while you fly it LOS and they can "look around" while you fly the aircraft.  However, neither of these Head Tracking modes can currently be used for recording any serious, cinematic video. Why? - because the P4/P4Pro gimbal appears to respond digitally to even tiny head movements - that is, gimbal movements appear to be incremental (step-based) and not smooth relative to head movements - no matter how slowly you move your head.  
2) With current firmware limitations, you must first connect your iOS or Android tablet to the P4 or P4Pro RC, power up both the RC and the P4/P4Pro, and then switch the USB cable connected to the RC from the tablet to the DJI Goggles in order to get past the 150 feet max distance from home point "Beginner Mode" limitation.
3) In my experience, the current apparent live video quality/resolution of the DJI Goggles when connected to the USB port on the P4 or P4Pro is poorer and more pixelated than the live video image displayed on my iPad Air 2 or iPad Pro 10.5" tablet when connected to the same RC USB port. I don't know why. The 720P/30 live view mode actually looks better than 720P/60 Smooth mode or the 1080P mode due to increased pixelation at what should be higher resolution modes. The apparent resolution of all three modes, in my opinion, looks more like 640x400 (or worse) based on the gross pixelation that occurs when the P4 or P4Pro is flying and the live video image does not appear to be able to refresh quickly enough to produce a decent image. There appears to be significant image compression occurring with the DJI Goggles connected to the RC USB port. Hopefully, firmware updates will improve/optimize this video quality issue going forward.
4) If you select 720p/60 Smooth Mode or 1080/30 HD live view mode with the DJI Goggles, you are restricted to filming in 1080p mode on the P4 or P4Pro (i.e., 4K video recording is not available in these live view modes). NOTE: The best quality image with the DJI Goggles with minimal pixelation and image compression is obtained by connecting to the HDMI port of the P4 or P4Pro RC equipped with an HDMI module and operating (on the P4Pro) in 5.8 GHz Auto HD mode. However, with the DJI Goggles connected to the HDMI port on the RC, you will also need to connect a tablet to the RC so that you can control the aircraft with the DJI GO 4 app running on the tablet.
5) I have been unable to successfully upload Flight Records that appear to be stored on the DJI Goggles (and only on the DJI Goggles) from flights where the Goggles were connected to the RC USB port and no tablet was in use. There is an Upload Records option on the DJI Assistant 2 app that displays a list of what appear to be Flight Records (file names all start with FlightRecord...) with the Goggles connected to the PC with a USB cable, BUT selecting the check box next to one or more of these records and hitting Upload Records results in "Upload Failed" message with EVERY attempt.

Overall, based on current firmware and DJI Goggles app software limitations, using the DJI Goggles is not the most user-friendly, immersive experience. Hopefully, DJI will continue to improve the firmware to remove above limitations and improve the user experience, just as they have done with all the DJI Phantom and Inspire aircraft I have owned over the past 2-1/2 years.

As someone sitting on the fence, re purchasing, very insightful, Thank you

Thank you so much for paragraphs 2 & 4 under "What Could Be Improved......".   Spelled out things that are not in user manual.

fans597f327d Posted at 2017-7-19 12:49
Thank you so much for paragraphs 2 & 4 under "What Could Be Improved......".   Spelled out things that are not in user manual.

fans597f327d,

You are welcome! Thanks for the positive feedback.  The current workaround to unexpected flight restrictions (distance limitation) when using the DJI Goggles by powering up drone and RC while first connected to a tablet with internet access and then switching USB cable connection from the tablet to the DJI Goggles is a pain. Hopefully, this bug will be eliminated in a future firmware update.

Ill address your negs according to your format.
1. not my expereince with the mavic. I find the the headtracking works smooth and seemless. the first person view has enabled me to find control over the aircraft beyond my expectations.

2. yeah its a pain in the ass to have to plug in the phone. But without a map in the HUD of the goggles it's for the best.

3. I'm thinking this is because you dont have a mavic. I'm not seeing any of that over here.

4. Again. Mavic.

5. That seems like somthing that will most likely come in an update.

Overall, I'm blown away by the goggles in conjunction wiht the mavic. It's not better with the goggles, its a whole diffrent ball game then before i got them. I fell like I'm finally able to use the mavic to its full potential.

What could be improved......(para. 2).    Switching the cables to get past "beginner mode" did work for me, but only until my P4 was restarted for another flight.  Any suggestions to get the goggles to hold these settings?  My RC has the hdmi module installed on bottom.

TheMann58 Posted at 2017-7-20 10:45
fans597f327d,

You are welcome! Thanks for the positive feedback.  The current workaround to unexpected flight restrictions (distance limitation) when using the DJI Goggles by powering up drone and RC while first connected to a tablet with internet access and then switching USB cable connection from the tablet to the DJI Goggles is a pain. Hopefully, this bug will be eliminated in a future firmware update.

What could be improved......(para. 2).    Switching the cables to get past "beginner mode" did work for me, but only until my P4 was restarted for another flight.  Any suggestions to get the goggles to hold these settings?  My RC has the hdmi module installed on bottom.

Yeah, I just got mine this past weekend. I was surprised how pixelated it is on USB. There is extreme compression on USB. I have an HDMI module, I am hoping to try it soon when I receive an adapter. Using the HDMI port on a computer such as FPV game playing shows what the goggles can really do. I hope some updates will reduce the pixelation on USB.

MegaTom Posted at 2017-7-20 16:23
Ill address your negs according to your format.
1. not my expereince with the mavic. I find the the headtracking works smooth and seemless. the first person view has enabled me to find control over the aircraft beyond my expectations.

Yes - based on your report and others on the DJI forum and various YouTube videos - it appears that, for now, the DJI Goggles are optimized for use with the Mavic including smoother response to head tracking, the ability to link the Goggles wirelessly to the Mavic, and a better video quality experience. Also, this means you just need the DJI Goggles and small Mavic RC in order to have an enjoyable, high quality video experience with the Mavic aircraft (and no cables needed!).

Unfortunately, for now at least, with the P4Pro and P4, the best video experience is via connection to HDMI output rather than USB, but that means you must also connect a tablet running DJI GO 4 to the RC while using the Goggles.  And using that HDMI connection to the Goggles (to get higher quality live video than the USB connection provides) also means no head tracking or ability to control the P4Pro or P4 operation (take-off, focus on P4Pro, camera settings, etc.) via the touchpad on the DJI Goggles - you will need to flip up the Goggles and use the DJI GO 4 app on your mobile device for that. I'm hopeful that later firmware updates will address current USB connection video quality issues when using the DJI Goggles with the P4Pro and P4.