I didn't have the beta, so it's all new to me. I'm glad they don't put the tabs at the top, but it would be okay as an option.
The great: It's FAST. On my 1.8GHz iMac G5 with Tiger, it smokes. It's not even in the same area code as Safari 3, Firefox, or anything else I've tried.
The good: 1. You don't have to deal with "top sites" - it appears you can ignore it altogether, and never see them, though apparently you can't turn it off totally. 2. You can separate the "add tab" button from the address window (by going to 'customize toolbar' and dragging the "add tab" button on to the toolbar - the other one disappears.
The okay: You can now put a limit on the history that's saved. Not too flexible, though - you can delete history after 1 day or 1 week, but not 2 days or 3 days (my preference). You can set it to 1 year - does anyone save their browsing history for a year? (Clicking "clear history" brings up a warning, asking if you really want to do that - an annoyance).
The bad: Tabs have an ugly shape, and are too dark. The top of the window goes from lighter to darker as you get toward the bookmark bar and the tabs (which should be lighter so they're easier to read).I don't like the disappearing "close" button on the tabs - I don't like that they disappear, and when they do appear, they're an ugly square shape, and just like orphans that were added on. It's like a 4th grader did the graphical designing of the window. Too dark!
The very bad: There's no toolbar button for "stop/reload" anymore. I use the reload button all the time (there is still a menu item for it, and a keyboard shortcut, but for me the button is much better). As for the stop button, hopefully web pages won't hang any more, and it won't be needed. One can always hope.