Roslyn will be good. It has to be because from what I understand, the MS team themselves will use Roslyn in Visual Studio and other products. Roslyn isn't just a public API for others to analyze code. It will be the foundation on which .NET framework languages will depend upon.
See Eric Lippert (Member of the Roslyn team, C# Principal) notes here:
http://blogs.msdn.com/b/ericlippert/archive/2011/10/19/the-r...