I didnt upgrade ,,my z2 tablet and i wont until im convinced its running at least as smooth as 4.4
I upgraded my z1 phone and i found that lolipop did some things good and some not.
Also xposed + dual recovery dont work that well at all. Plus i found my system slower than before ..
For those reasons and some more i ve chosen to stick with the KK platform for a while longer on the tablet ..