Honestly speaking i was never a fan of TDD till few months back, but the more i read on this topic the more i am facsinated about it. Not untill I read Agile Principles, Patterns and Practices by Robert C Martin, where he talks about the relevance of unit test to validate both design and code smell.

Okies let me brief out some of the new cool features of xUnit.net

Things i liked of xUnit.Net compared to NUnit

• Single Object Instance per Test Method.
• No [SetUp] or [TearDown] - replaced by constructor
• No [ExpectedException] - appropriate exceptions at relevant line of code
• Aspect-Like Functionality.
• Reduced the Number of Custom Attributes.  i am fan of AOP

Most liked

• Use of Generics.
• Anonymous Delegates.

for further reading refer codeplex