I've been enjoying most of what's "new and improved" in IE7 for over a year now using a wonderful little product called Mozilla Firefox.
That all being said, it's a beta... A Microsoft beta at that, which is what would be considered a rough alpha for most serious developers. You have to expect there will be some bugs and not everything will work right. I plan to stay as far away from it as possible.
I have the current version of IE 7 and all I got to say is that they still need to work on fixing all the bugs in it. I downloaded a security patch for it and so far it seems to be working for now. I hope it stays that way.