I'm going to keep this short and sweet, here were my first impressions using Visual Studio 2010 Beta 1...

The Good:

In Silverlight 3, when using the UriMapper to rewrite navigation urls or styles on controls that require a reference (DataGrid, DatePicker, etc..) in App.xaml, the Visual Studio xaml designer still worked. 2008 had bugs that broke the designer views in these cases.

The UI seemed nice and clean, certainly an improvement over 2008.

The Bad:

When i first installed it then tried to run it, it crashed. Then after rebooting, it loaded my solution fine. First time building caused it to crash again.

About 50% of the times i built my project, it would say build failed, but wouldn't give any message of why in the output window. Without changing any code if I built again, it would work.

Every few minutes it would freeze and I'd have to end task.

Within a couple minutes of use it was taking up over 500mb of RAM. That's fine on my 4gb box but VM users beware.

After uninstalling it, no .NET programs worked anymore. They would give .NET 4 errors about missing dlls, even though they weren't apps built using .NET 4. After uninstalling all of the .NET 4 components and repairing the .NET 2 and .NET 3 installs, the .NET apps started working again. It also kept the ASP.NET State Service pointed to the .NET 4 directory, so I had to use sc delete and sc create to reset it to the .NET 2 directory.

Conclusion:

I wasn't able to get too in-depth into VS2010 due to how unstable the product was, but the improved Silverlight designer support was a plus. Needless to say, I won't be touching it again until a more stable build is released...