We've done some testing on 2010 to incorporate the support and test the update, but we haven't moved any production machines over to it yet, so I don't have much working knowledge of the IDE or any idiosyncracies. I know that Trent's impression of the new version has been good, barring the usual speed bumps that had to be navigated to get the designer and add-in support for SF funcitonal and reliable. As soon as we start migrating our projects over I'll be sure to check back in with any additional findings and impressions.