With all the bug reporting and error corrections and such that are being reported - I just wanted to be sure you know how much i appreciate the effort you're going through. I mentioned somewhere else that I've done my share of site conversions so I understand what you're going through (I once had to tear apart a database manually to convert from one platform to another and still keep the userbase and posts from the previous incarnation, that's how bad it got).
Anyhow, I just wanted to be sure to get in a good solid Thank You!
And some of the features i like from the upgrade:
the right hand column on the forum front page - showing a condensed version of the latest posts, AND the optional shrink/expand button for it, very nice.
The new attachment manager, once I got used to it, it's also very nice.
The title prefixes from the Map Requests forum, I see that being very useful for the future
I'm sure there are other things i like that are new, but those are what come to mind at this particular moment.