1. Screen real estate has been given back to the user with the omission of the File/Edit... menu system. Google's take is that we really do not need that technology. The message they're sending is that the content is what's most important, not the adminsitrative functions.
2. It's the tabs that encapsulate the experience - and because of that, the integrated URL and Search field are within the tabs, not the other way around as in Firefox.
3. The URL and Search fields are one and the same - it's integrated. Now is the time when simple english can be entered into the URL field instead trying to remember some dot-com address. You can also choose your own search engine for this integration (though I haven't tried anything other than Google just yet). This in turn means that search engines will be more important than ever in managing content on the Internet. It's a push that helps Google's business model.
4. I can't seem to find my bookmarks in a way I'd like to access them. It's using cascading menus instead of the stationary left-panel which requires more motor control - which could present a problem to some less-abled users.
5. Well, I just demoed the application to my colleague showing the integrated URL and Search field and it just crashed my Firefox as it was running at the same time. Bug!
6. Transparent administrative and status functions - they don't appear unless you want them or that they show something important. I'm guessing the whole idea still is to give the screen real estate back to the user.
7. When creating a new tab to view, you are instantly brought to your most visited sites as a layout preview as well as a short list of the most recent bookmarks. While this is a great idea, I'm not always insterested in what I've just viewed or bookmarked. It's a good thing they've kept the "Open in new tab" function when I come across a link.
8. It's much faster than Firefox 3.
I'll be adding more to this in the near future so please stay tuned.