Seconded with enthusiasm. Eric writes at great length about the detailed decisions that go into programming language design, especially revision of an existing language. Even though I should know better, I have been guilty at times of "how hard could it be" syndrome. Reading what Eric says has cured me of that disease. (for programming languages at least)
I agree with this. At first glance the problems he presents are simple, then you realise all the design decisions they've made and the pros and cons of each approach they were aware of when writing C#.
On a footnote I also recommend Jon Skeet: Coding Blog - http://msmvps.com/blogs/jon_skeet/
He's known in the .Net community. He's the guy behind Tony the Pony. He's a Google staffer who has written some C# books. He goes into great depth about C# stuff.