I wrote a post a while ago criticising Orcas Beta 1 so I suppose its only fair that I write about Beta 2. I have been using it for a few months now, and have found it to be excellent. I have only discovered one crash so far (to do with intellisense, and apparently fixed already for RTM).
The multi-targetting feature is superb, and the WPF designer has improved a lot (you can create a click handler for a button by double-clicking), although I can't seem to find any way of browsing other available events and adding handlers, short of using the intellisense in the XAML file. Some of my other criticisms still hold true - there is no help in setting FontFamily and Ctrl-Click copying of controls doesn't work.
Silverlight support is sadly not going to be built-in, although to be fair, Silverlight 1.1 has still not been officially released. Having said that, the Silverlight development story is very good in VS2008 compared to the pain of working on it in VS2005.
Overall though, I'm a lot more enthusiastic about VS2008 having used the Beta 2. What is even more exciting is the possibility of using the new C# 3 language features against .NET 2.0 projects. This is a really compelling reason to upgrade even if you have no intention of using the .NET 3.0 or 3.5 libraries.