You can edit projects using both Visual Studio
2010 Express for Phone as well as with Expression Blend for Phone (which is
also included for free in the download package). The project file format is
the same for both tools - enabling you to create an application in one of the
tools and then open it up and edit it in another.
Expression Blend for Phone provides a really
powerful environment for creating interactive experiences:
It includes full designer support – including support for
animations, storyboards, custom paths, and many other features. It also
uses the same phone emulator as VS – enabling you to build and run applications
without needing a physical device.