I just disinstalled IE 9 beta from my pc. The main reason is that when I use the middle button to open a link in a tab, I get a white page. And since I use a lot the middle button...
Anyway... I don't like the merge of the search box with the address box. I usually use google suggestion for my searches but I don't want that every address I write goes to google. If you really needed to save space at the top of the view, why didn't you use a disappearing address box? Even Chrome (and I think it's... ugly? yes, at least) has a better solution for the address and tabs bars...
I really thought it was better before I installed it..