1. No ViewState or "surprise crap".
2. Faster server-side.
3. Simplified model for multiple related views.
4. Unit testable.
Room for Improvement:
1. Difficult to convert an existing site.
2. Not best for SEO out of the box.
3. Challenges if you’re not running IIS7.
If I needed to build a new site from scratch, and was able to use IIS7, it would be extremely likely that I would choose ASP.NET MVC. It’s a joy to work with (possibly because it’s "new"), and just makes sense. If I needed to work with an existing site, I would certainly have to consider the pro’s and con’s I mentioned above. ASP.NET MVC gives us an amazing new tool in our huge Microsoft toolbox.