I have an interesting relationship with Pantera and Dimebag since Pantera got me into metal but I don't much like them anymore.
Dimebag's solos are great, he has some good riRAB, but he also has some really crap ones. I don't think Pantera's style is too great... for example, Walk. The 3 note riff is fairly average from the onset but nevertheless, used properly, it could be effective. However, Pantera repeats that one riff throughout the whole song and it becomes pretty boring.
It's mainly Pantera's groove style that pisses me off. After all, I think Phil Anselmo is actually a great vocalist (check out his stuff in Down), and the other two musicians weren't too shabby. It's just the style IMO.
So I'd agree that Dimebag was a good guitarist in a bad band.