Well, that was easy...
To expand on my rather brief post, the Confuser gives you a less thorough test than the questions in the Thom books, but gives you a genuine feel for the actual exam. Pass a Confuser exam and you can go into the Real Thing confident that there will be no surprises. You could almost certainly use nothing else and pass, although it wouldn't be smart to actually do that...
The usual caveat is that there are a few errors, but it isn't bad. If you've done the bookwork first then most of these stand out.