I'm a newbie Lumia 800 owner and here's what I've found so far with build 12220:
1, The camera app adds a greenish tinge after a photo is taken.
2, Battery life is pretty bad sometimes requires a full charge twice a day
3, The compass is completely out of whack by 90degrees (southern hemisphere issue) rendering the fancy Nokia Drive and Nokia Maps apps useless.
I'll concede that #2 is likely related to the hardware itself, but the other two fall squarely in the software camp.
I like the general usage of Windows Phone OS, but these bugs are really tarnishing the experience for me.