Although WPF itself is unchanged since the December CTP, the "Cider" Visual Studio integration in the new release shows the benefits of a full coding milestone. The main differences in this release include an improved grid experience and the ability to read project references.

Just as a warning, in current builds the "Cider" designer is only available on the full version of Visual Studio (Professional and above) - if you install it on Visual C# Express or Visual Basic Express, you'll only get the IntelliSense and templates, rather than the tabbed design view.