It is first discharging after downgrade SE to 9.3.5 so it's indexing, getting cache and so on... But in my opinion it's working better than 10.0.2 :
*no problems with battery drain (only 2% by night )
*back to old messages without childish view
*slide to unlock will help in winter and unlocking by fingerprint are faster than on newest one
*battery last longer and there are no dropping % I had last days (had full discharge and only 87 cycles )
*wifi speeds are better (120 vs 150 on 9.3.5 )
*mail app is working as it should - no translation glitches...
*in reduce motion it's faster
Overall 9.3.5 looks like old business iPhone not entertainment device we have on iOS 10.
Glad to downgrade and have fun being beta tester on GM ones
iPhone was set as new - glitched iCloud 2- stage login did not sent me codes and had it blocked for like half hour when switched SIM card with old device - had no messages and was unable to make a call...