Just downloaded and installed 2.3 on my Canon 5D MkII. Love it for the most part - the HDR, focus stacking and intervalometer is awesome stuff!
My biggest nit is I can no longer use the zoom button in Liveview. I can do Magic Zoom and set that to do 3:1 but it's still not as good as a full screen zoom for macro focusing.
I almost have to believe it's a setting but I'll be dipped if I can find it and I've darn near been through them all.
Secondly - I went to try again after a day and the camera was dead from an almost fully charged battery yesterday. I double checked and no functions like intervalometer were active. I stuck in a fresh battery and will check later for battery drain. It is my assumption that unless you are in Liveview standby or a timer function is active the drain should not be any worse. Is this correct?