sorry, but i read this OP as he would criticize only the really customer-unfriendly strategy of ibuygou and i could not read anywhere that he claims that all xiaomi devices are doa.
you have to enable developer settings by pressing 7 or 8 times on "Build-Nummer"
then you will see more settings in settings.
edit: ok, micha was faster. :)
OS Monitor says build date of adreno-egl on CM11@mi2 10/15/13 instead of 04/15/14 as mentioned in http://forum.xda-developers.com/showpost.php?p=52042968&postcount=297
But i don't know if this is somehow relevant for us..
old post, not sure if you still need it, but google released "*no-support-for-this-app-on-this-forum*" in playstore with photosphere, and it is working.
https://play.google.com/store/apps/details?id=com.google.android.GoogleCamera
I would make a backup, wipe everything and start from scratch with tdb on rather than trying to fix strange bugs which may just appear because you just (dirty) flashed cm11 over cm10.2.
Maybe you also should increase your system partition with m1chas script.