EntityFramework + LINQ is an amazing combo for getting things done quickly. And Visual Studio provides the best debugging experience I've ever had. Couple it with ReSharper[1] and you're in code heaven. At least until you run into one of the INT_MAX subtle quirks of C#/.NET, at which point you feel like throwing your dev machine off the roof.

[1] http://www.jetbrains.com/resharper/