[pdwetz]

I can't speak directly to the differences with Unity, but comparing C# from .NET 2.0 to the latest you're missing: LINQ, dynamic data types, extension methods, optional and named method parameters, covariance and contravariance, async and await... and a whole bunch I'm probably forgetting. It's a lot more flexible now and lets you take advantage of dynamic/functional code. After coding in 4/4.5 for awhile, I certainly wouldn't want to go back to a 2.0 ecosystem.

[socialist_coder]

Extension methods work (I use those all the time), and async and await are unnecessary because Unity gives you coroutines and yield.

The rest of that stuff seems cool though. Oh well =\