CodeDOM doesn't work everywhere. In particular, you're gonna have a rough time porting to iOS (so it's not a viable solution for cross-platform game scripting, say).

For a long time I was one of very few people who ran into the problems this solves, so I'm sympathetic. As I posted in my other comment, though, I think Jint does a better job of solving this problem in the way Mond does.

I wasn't really satisfied with the existing scripting libraries available for C#, many just bind to a native implementation or have terrible interfaces. I wanted something easy to use that would work (almost) everywhere without any hassle, even if it means performance suffers.

-C#: http://www.csscript.net

-C#: http://scriptcs.net

-Cobra: http://cobra-language.com

-Boo: http://boo.codehaus.org

I'm always a bit skeptical of the libraries that generate IL. One of the biggest reasons I consider scripting is to support hot swapping, but the CLR doesn't do a good job with that.

I have used CS-Script before and it's decent. The assemblies it generates are eligible for garbage collection (if you use CSScript.Evaluator) but it also has annoying limitations. Everything must be defined before it's used and must be in one file.

ScriptCS/Roslyn?