Currently running 4.2.0, since one
mod I still use hasn't been upgraded for use with 4.2.2 yet (although it is suppose to soon and then I'll upgrade).
All upgrades I've done thus far I haven't had issues with, but I don't have any experience with the upgrade to 4.2.2 yet.
It seems that many of the issues originally reported by those upgrading to 4.2.2 were worked out with a few tweaks to the upgrade process. The rest seemed to revolve around numerous 3rd party mods that weren't compatible with php 5.4, which many were moving to at the same time.
Do you remember what issues you initially had?