I've been having a play around with Windows Blue Beta 9364 and have created a few screenshots showing differences from Windows 8. From what I can tell the "all programs" button is removed when you right click on the start screen, the best improvement ive seen so far is that you can resize Metro apps when one of them is pinned to the side of the desktop. Not bad if you want to use a Metro app and your PC at the same time. I still think third-party apps such as ModernMix already do a much better job to be honest. Other than that I have not seen much to get excited about at the moment, it's mainly changes to the Metro interface such as more options been added in e.g. changing the screen resolution, and an option to size the tiles even smaller like on Windows Phone 8.
Microsoft really put some work into this windows 8 didn't they. Really looks loads different lol. What a joke.