I'm using VS2008 on a production project now and I'm very pleased (still using Winforms, not WPF). LINQ to SQL has a few oddities, but so does every ORM tool out there. Overall, our productivity with LINQ to SQL as the ORM tool has greatly increased, and now we're writing LINQ queries instead of waiting for some DBA to write a simple stored procedure for us. I'd say that makes the switch worth it. Nothing out there is perfect, but don't be afraid of something out there just because it's new or different.