I'm able to get ~20 minutes down to 23% on medium fast flights (going up to 14 m/s in light wind) consistently with an X5S.  No reason to fly a single flight any longer but I appreciate the 'insurance' in case something interesting pops up or if something untoward happens on a long flight.
The spec is 27 min with a lighter X4S - so I'd discount about 2 minutes for ideal conditions max flight time for a X5S.

Anyone familar with non-military, non-industrial tech will appreciate that battery life spec sheet numbers are slightly inflated. I wish DJI wouldn't follow the Joneses now that it is pretty much the undisputed top-dog in the consumer /prosumer space for drones but we have to wait to see if they change. Still, here's some tips for interpreting battery life claims, albeit for laptops but the principles still remain.

http://www.mitteq.com/2016/01/th ... e-test-of-main.html

Who's happy and who's not with this new aircraft?

I love mine, had teething problems when it came.

a) rattle from red props
b) white props a bitch to fit and remove.
c) battery issues (cant use only one)
d) calibration of IMU was not explained in the "manual and had me lost for a long time
e) the manual is inadequate. I think it should be the quick start and a more detailed manual teaching all the new things (and old) so its a good reference point if you get issues
f) DJI support is very disappointing I paid for the "refresh programme) that promises a dedicated technical support via a dedicated team (pity they don't work for DJI and are out sourced ) reading from a script made me so angry
g) no lens cover for the X4S
h) no basic tools such a T8 star driver
i) if you have never had a DJI product before it don't tell you anywhere how to turn on the batteries

So i spent sometime going over every millimetre checking it was at my expectations.

Now almost 2 weeks later i'm impressed. On a point of over estimations by DJI i found just the opposite in sports mode spec says 58 MPH I get readings by happydrone website says 82 mph (no tail wind) and if you release the forward stick at these speeds it was an impressive thing to see !! and the gimbal was able to account for the rapid and steep angle change on the camera.

      

Dr Jon Posted at 2017-1-15 23:11
I love mine, had teething problems when it came.

a) rattle from red props

Ha Ha to point (I) - turning on the craft. DJI's power on and off  logic is pretty standard. There are phone power boosters involving sliding that are sure to drive anyone crazy.

The manual is pretty decent. I read it too, just that some things are not where you expect to find them. There are also FAQs and videos on their website that a diligent person like you might enjoy going through. To get a sense of how far DJI has come in 3.5 years, see if you can find a Phantom 1 manual and try to understand it...
The bird can fly very fast for sure. The max speed mentioned is what they think is the limit for usable video with the provided lens. This point was made in an earlier post that defended the reduction of the official spec.