Just want to shortly give you a positiv reply on this topic: I started mapping after seeing JK2 and reading this tutorial.
I hadn't mapped since early unreal days and even there my experience was very limited. With the help of Bubbas Tutorials and GTKRadiant I have mapped now for the past 2 weeks and I think my results
So if I can do it almost everyone can do as good. I don't know everything but I think I know enough to build the images I have in mind.
Just wanted to let you know