Wow, can you believe the new versions have been with us already for one-third of a year? Time flies! I launched a site using the new versions shortly after release, so I'm happy to say that my experience in production has been mostly positive. Here are some loosely coupled thoughts...
First off, the IDE is a leap in the right direction. Compiling stuff in particular feels much faster. The only real performance complaint I can find involves the rare case where I need to switch from code view to WYSIWYG when dealing with HTML. And heck, that might be caused by ReSharper for some unknown reason. Ditto for the crashes I get frequently when editing CSS. I don't find the CSS features that useful, so I don't encounter those problems very often.
On one hand, I like that the framework now ships with all of the right goodies together, including the AJAX framework. What I don't like is the mess of a default web.config you need to get it all to work. It has not grown gracefully, and it's a pain to manage as you migrate older stuff to v3.5. The further distinctions using IIS7, which I haven't had to use yet, are also annoying.
I feel to a certain degree that VS isn't "done" without ReSharper, and I'm anxiously awaiting JetBrains to v4 moving forward. The most recent nightly builds are actually pretty sweet and mostly work, but every once in awhile it dies and brings down VS with it. That's the price you pay for being an uber-early adopter, I suppose.
The client-side debugging in IE is hit or miss. Sometimes it doesn't work, and I'm not even sure why. More often than not, I find myself ending up in Firebug and debugging that way. I think the biggest complaint I have is that it's still meant to work around the F5-and-run model, which is still not ideal in the Web world, where the URL's you use may frankly not even map to actual files, or you want to run off some current form state or user session data.
Beyond those minor issues, I'm enjoying the tools, and when I actually manage to buckle down and get something done, it's fun to write code.