Which network are you with? I've just checked and no update for me yet on O2

 

I have just had my replacement EE and no update from V10K. My last one I had rooted and running Genysis ROM V20C which I felt had improved battery and performance, but that could be tweeks in the firmware. V10x is 5.1.x, V20x is 6.x, if we get V30x it will be 6.5.x or whatever "N" will be after Marshmallow.
Strange that it deleted your apps if you didn't Factory Reset too though. Perhaps if you came from LP to MM it needed to clear out properly to save conflicts, I don't know. But if you were already on V20x I really see no need to delete any data unless you selected to (which is advisable after an update anyway to guarantee best performance etc and save any conflicts, obviously after backing it all up).

 

My G4 (unlocked on Talk Talk/vodafone) updated to V20d on 02/02/2016. Since then the user interface has been frozen every morning and will not swipe until "UI has stopped working" error message eventually appears and it restarts, after that all is fine.
I did not notice any apps getting deleted though.