Well 98% of whats on that thread are NOT 9.2.1 bugs. Some not even bugs and some carryovers from iOS 7 and 8 and 9. So that wiki is pretty useless currently as it does not show what 9.2.1 broke or fixed specifically. Who said ZERO improvements anyway? You think Apple is going to release a new version just to be doing it? One thing I saw mentioned elsewhere was the MDM issue for enterprise was addressed. A few posters have said performance seems to have been tweaked. But I would not expect a lot from a x.x.1 update anyway. However ANY improvements or security fixes make it worth the 5 minutes to download and install as far as I am concerned.