Well, the switch from Classic Blogger over to Blogger Beta has been both a blessing and a curse.On the curse side, the biggest problem is the mess-ups with my feed. First, switching from Classic to Beta itself makes your feed reissue your last 25 posts. Then, making changes to html on older posts--even if they are not on your main page--reissues those posts as well, which not only show up on my 5-most-recent-posts section on my sidebar, but also on any aggregator that subscribes to my feed. (Sorry, guys.) Also, somehow, a few of the older posts to which I was adding labels reissued while others didn't. Go figure. In addition, there were some problems with layout when I switched over, like losing some html driven sidebar features. Those were easy enough to fix, though.
On the blessings side, the labels section (after you get through re-labeling all your old posts) is a wonderful addition to blogger. Also, the new layout feature is so easy to work with. It makes it easy to edit and rearrange your sidebar sections, as well as add new ones. Plus, most features Beta doesn't have, you can add using their html/java feature. I've also noticed that creating posts moves a lot smoother.
Well, that's my experience in brief. If you're moving over and have any questions that I can help with, just let me know. Blessings.