Updated from fully stock DI18.
Negatives: My GPS is definitely dead like many others have also reported. Every time I turn on the phone, the media card scan comes on and takes quite a while, and the same thing happens when I go into the gallery.
Positives: Touchwiz itself seems smoother and seems to be less subject to random lags. The stock music player is much better. Ditto for stock messaging. Flash works well from my tests. It seems like I gained internal memory.
I hope someone finds a fix for the GPS for us stock users. I would like to keep this update and get it working to as close to 100% as I can get it.
If not, I'll have to go looking around with how to flash it back to stock 2.1 again.
