First off, I'm liking it alot, finally an IE that is fast, good work.
But when it comes down to it I simply cannot use the tabs-ui. My average is at least 10 tabs, and sometimes many more. I realize you can't display 50 tabs efficiently at once, but limiting it to what, 3-4 at once? I would really like to understand the reasons behind this. If your average user really only has that many tabs open, and you specifically cater for them, the please don't be suprised if no advanced users will ever use it.
The other big thing for me is addons-support, specifically greasemonkey and ad-block plus. What work is being done to enable such addons in the future?