Buy it. I like them. They look good and if you get the GIAC (or similar product) chip it will be FAST! Just make sure you do all the recommended work (fuel pressure increases, etc.) before you install the chip so that the engine gets plenty of fuel.
A neighbor of mine had one for a little while. It was an auto, it was lowered, had 17" TSW wheels--it looked good. I'll post a picture. Here's a list of his problems.
The 240 hp that he was putting down through the five speed auto was apparently too much for that transmission. He sold it before he killed it, but it would clunk into fifth gear from time to time. Manuals are more stout if I recall correctly. This was almost certainly a product of nearly tripling his boost pressure from the turbo.
He killed MAF sensors like it was his job. Again, almost certainly due to the huge volume of air that was shooting through that thing.
The seats apparently kill specific airbag sensors when you move them throughout their lives. If you're buying a 98, this problem is probably just around the corner.
He got all sorts of CEL codes. This, again, was almost certainly due to the chip and all the other engine work he had done to the car.
Moral of the story: if your brother wants the car, he should definitely buy it. But he should have some maintenance performed (like everyone recommended above). Also, if he wants to keep the CEL (check engine light) off, he should refrain from changing things on the engine. However, if he doesn't mind ignoring the CEL, the car can be made to generate huge amounts of power and 150 mph runs are not out of the question.
www.vwforum.com (or maybe it's plural and www.vwforums.com - I can't remember). That's a pretty good forum. It's not like this one (you get flamed a lot if you don't use the search function), but it's full of generally good people. I knew a lot of them for a while.