Street Fighter is without doubt the greatest fighting genre gaming franchise in the history of video games. It's balance of characters, wacky back stories, fighting mechanics and overall look and feel across the various titles is unrivalled (don't mention Street Fighter EX :-/).
"Street Fighter III 3rd Strike" is reckoned by many to be the greatest Street Fighter game. Well SS4AE is like a heavier, slower version with a great new art style. They've tweaked the mechanics to make it more accessible to new players (easier to pull off special moves) but it still has the depth required for the hardcore gamers. Very good indeed. It's given me many, many hours of fun.