Moving from SVN to TFS has been an interesting experience. The integration of source control directly into Visual Studio seems like a good thing, but even on a well set up network it can occasionally bring Visual Studio to its knees. And I still don't trust its automerge.

Anyway, if you find that the TFS diff and merge tools are just too ugly and odd to work with, there's a great page on the MSDN blogs that describes how to set Visual Studio to use your preferred tool:

Welcome back TortoiseMerge, I've missed you.