Since the acquisition of .NET Reflector by redgate , it is the major release with couple of exciting new features. you might have tried reflector, it decompiles .net framework assemblies. But when you will install v6, it not only installs standalone utility but also an add-in integrated into Visual Studio. I am going to state couple of benefits of .NET Reflector Pro that I used and found useful:
1- Decompiles 3rd party .NET assemblies from with in Visual Studio.
2- Step in and debug code of 3rd party assembly as you do in your own code.
.NET Reflector v6 is free and .NET Reflector Pro v6 is available free for 14 days trial.