I don't like the interface either, you can't tell when it's doing something CPU-intensive in the background like compacting unless you notice that it says something in the status bar, and the status bar changes when you do something, leaving you wondering what the hell it's doing.
I installed the new beta a few hours ago and it seems just as bad, just now it was sitting in the background and it made my brand new macbook slow to a crawl for some reason. so I tried telling it to do the new archive feature on my inbox, and it gave me a folder for the years 2005-2009 with an extra folder for 2000 with nothing in it, and the 2005 folder ended up with a bunch of messages from 2005-2009. awesome. it's still hanging for long periods of time just trying to open single messages. I'd say it's my fault for using a beta but the release isn't really any better.