I have heard so many negatives after this May update,it worries me some. I am new so here is a newbie question. Can you still fly when an update available is showing?

Yes you can. Lots of folks don't even update. But it is recommended.

Quite frankly I would not hesitate to update, there is no "roll back" update so ask your self why. There is a problem with the previous version that DJI do not want you to encounter, my guess is the issue under certain conditions whatever they are could cause you to have a warranty claim which means either a fly away or a crash.

How many Mavic airs do you think they sold worldwide so far and how many issues do you see with version 400. Virtually none. Upgrade your software or not it is up to you. I can assure you DJI don't want you to upgrade because they like watching you upgrade software but rather that the software is better than the previous version.  I will bet you that there are thousands of aircraft running on version 400 without a single incident. I will also bet you that version 500 will be better. If you leave it on the current version and you do run into problems I can assure you they will not be sympathetic to your cause seeing as they have advised to upgrade.
I would advise that once you upgrade that you do a factory reset and recalibrate everything. DJO says it is not required but there is always the chance of some old code or settings values being left where they should not be.

Agree with KevJones ( @#3 )... this update indicates some fixes that appear to be safety related.  If you have one of the aircraft for which any firmware or G04 indicates fixing an item that could cause harm or fly-aways, I wouldn't hesitate.  Otherwise waiting a few weeks can make sense... to me.

I updated and got the motor current error on my second flight. Also had an issue with the quad yawing slightly when hovering without any inputs from me. Hopefully it gets resolved.

Update, no other way about it. Over time the wheat will be separated from the chaff. It is in your best interest to do so.

You can bypass the firmware update to Go Fly, but not updating firmware could put your drone at risk and DJI always recommends to update the firmware immediately upon connecting.

davidmartingraf Posted at 2018-5-9 17:55
You can bypass the firmware update to Go Fly, but not updating firmware could put your drone at risk and DJI always recommends to update the firmware immediately upon connecting.

Yes but not when this most current firmware seems to trigger the SAME error that so many had experienced! It's so disappointing that this happen....

Best way to decide on whether to apply latest update is to wait till the Bold have gone before you, and reported back.
Decades of experience with even tested and blessed updates taught me, unless update is absolutely critical, you are best holding off for a while.
Sometimes problems with an update comes from localized settings or localized usage that system used for testing did not have.  

We always recommend that users upgrade the latest firmware because it's the optimization to the previous one, but that depends on you. If your drone's now performing fine and you don't want to upgrade it, that's alright.
Besides, if anyone has issues with the firmware upgrade, please kindly contact us. Thank you.