I haven't read C# In Depth for 4.0 yet, but I would suggest that you should not pass on the 3.0 version. Here's why.
C# In Depth is not like a technical reference book where the author rehashes the same information what you can find on your own at MSDN. Jon discusses the evolution of language starting from C# 1.0 up to 3.0. I sincerely wish that all technical books were written like this. If you are still not convinced and want the cofnirmation from someone more authoritative, let me point you to Eric Lippert's forward for the book.
Eric Lippert is a senior developer on the C# compiler team and his blog is a must read for all C# developers.
Coming to the main point, my guess is that Jon may be skipping on some details in the new version of the book which he has already covered in the current version. And I think it would be great idea to learn about the choices/compromises made by the language designers.
Thank you. It occurred to me that it would be nice if the pre-generics artefacts were somehow erased from history. (They're essentially clutter in a space that's getting fuller and fuller, right?)
