After playing with VS2010 Beta 1 for about 30 minutes tonight, I’m honestly a little blown away.  I knew that Microsoft was changing things up seriously in the UI department, and I’m impressed at first glance.  A few notes along those lines:

• If you’re using a dark theme, by default, the text editor uses a white background, meaning you will have to go into the Options to reset the background to the dark color.  The funny thing is, the settings are actually correct when you go in there, but it doesn’t apply them to the Text Editor until you look at them.  As a further note, it seems you have to do this for each different type of code you look at (C#, SQL, HTML, etc.)
• The dark blue frames are quite attractive IMO, and do a very good job of separating out the various panes within the IDE
• As is typical with beta IDEs, the performance isn’t quite there, and it had some issues recognizing a LINQ DataContext in a .NET 3.5 application.  Not sure if that’s going to be the case for all projects, but we’ll see.

Overall, bravo to Microsoft for a big step forward.  I’m looking forward to playing around with ASP.NET 4.0 Beta 1 and especially things like customizable ClientIDs for Server Controls and the improved JavaScript Intellisense.  Kudos again to MS for a job well done.