Some new things I noticed:
- The new dock taskbar actually works! There are still some minor bugs, but then, this is a beta. The dock taskbar functions somewhat similarly to the Mac OSX dock, except with way too much eyecandy. This can either be a good thing or a bad thing.
- UAC by default isn't as annoying as it was before. Its more inline with what Ubuntu does with the sudo dialog for administrative tasks, but the UAC popup frequency is a little too frequent for my tastes.
- Those taskbar status icons are consolidated to a small popup window. No more long list of status icons invading your dock any more.
- Sidebar dock from Vista is gone. You can now just add Gadgets directly to the desktop.
Application compatibility is currently an unknown, but I will be installing some games to see how performance is with the current beta. All things said, things appear to be more responsive and whatnot, so we'll see how it holds up in the next couple weeks.
Obviously, things might change when they release the final version of Windows 7, but these current changes from what I've seen are good.