Soul Calibur II for the GCN is marvelous, especially with the addition of Link.
With the tag team features, and the tournaments, and the arcade mode it all balances out to be a ****-ton of fun. Especially with friends. This is the best Soul Calibur out of the series; and there has been five of them. Arguably, the 5th one was the worst out of them all.
Overall, if you're looking for a challenge and love fighting games. Then knock on Soul Calibur II's doorstep. It's bound to surprise you with a few punches.
(Um? Horrible ending to a review...oh, well...)