Proud owner of Lenovo K900 as well.. joining the k900 family here... 

been using this phone for about 2 weeks now..
does not hang at any moment..
do experience some lag in certain games like minion rush(btw, to play the minion rush requires gyroscope.. so this phone does come with gyroscope)
heats up pretty fast.. camera is awesome, i mean really really awesome..
signal strength pretty good too.. speaker is loud n clear.. voice from calling is good also..
lack of sd card slot is a bit sad.. but overall brilliant2 device..

btw, heres how i set up my k900
k900 voxis

i got that setup from another video on utube.. coldfustion.. his videos are very good..

here's the link..
lenovo voxis tutorial

just follow the video step by step.. its quite easy to do.. simple.. no root needed(in case u r wondering)

u see, my frens very impressed with that setup.. its kinda match the design of k900.. making it looks more exclusive compare to using the lenovo launcher..

gud luck..