ASP.NET MVC Preview 5 dropped a few days ago and I upgraded my apps today.  Just a few minor notes on the process, which was painless. Most changes are covered in the release notes.

• RenderUserControl is now RenderPartial
• Asserting that Controller.View() was called now looks like:

Assert.That(viewResult.ViewName, Is.EqualTo(string.Empty));

• Some HtmlHelper changes.  Some are great but the behavior of the private method InputHelper has me a bit perplexed.  It outputs a hidden input for holding the value of checkboxes. This violates a big selling point of ASP.NET MVC in the first place: it won't write unexpected HTML.  I guess I'll be writing a lot of these guys, but testing them is painful.. otherwise I wouldn't much care what came with the framework.
• DefaultControllerFactory.CreateController() is now public
• action filter contexts no longer take a MethodInfo object as constructor param..

That's it from my log… again, pretty easy upgrade.  I am still reviewing all the changes.  Besides the HtmlHelper stuff I am excited about this drop.