I am in the camp of "I like the new UI, for the most part."
That being said, here are the reasons. (I don't do swoopy stuff so I can't talk to that part of it if it's different.) The new UI has made me faster because of less mouse travel and fewer mouse clicks overall. I use a lot of hotkeys, and the combination of my standard ones, the new S shortcut bar, and the flyout context menus, I almost never go to the menus at the top - only on rare occasion do I need to fly them out. Yes, I have them hidden and only fly out when needed.
When I first started the SW2008 beta testing and tried the new UI, my first question was "Where's my stuff??" And that's the first question from people here. But with one gentleman that doesn't appreciate change, once I spent
20 minutes with him to show him that most of his stuff was at the cursor, by the end of the day he liked it. I have customized the shortcuts to the way we do stuff and find that expecially in a sketch, just about everything is available at the cursor.
So, if you are willing to give some credit to the folks at SW in that they did actually think about the overall user experience, then it's worth a bit of time to give a good try to learning what they changed and why. I had the opportunity to talk with some of them about it and I can tell you that they do consider the effect on the user. I won't say there aren't any bad decisions, because there are some I don't agree with. But for the most part, things were done with the purpose of speeding up the user.
If you wish to try my settings as a starter, let me know and I will send you my file. It's a good way to start with the way we are using it, look at what we changed and why, and then decide what you like or dislike.
WT