I personally like v21 better than v20, as I can run max shaders fine with 70-100 fps even on 100k brick servers (I understand that some people can't run them as I used to be one of them before I finished my new desktop).
But I did like the terrains, and still miss them, but the shadows make up for them in my opinion.
Also, I noticed less bugs and less lag while playing as well as shorter download times for server files.