Many have had to do a Factory Reset (Wipe Data & Cache) to get the update to run smoothly.
I had an additional problem with froyo roms. None of them ran on my Droid without freezing, lagging and having FCs and totally unresponsive screens (screen, soft keys, & power button). It turned out to be my memory card. I had to reformat it and everything has been smooth, including great battery life since.