High HP, Speed, Attack making it an excellent revenge killer. Excellent typing (only two weaknesses), double STAB on Outrage and Earthquake which hits almost everything for SE or neutral damage.
Plus its a hammerhead shark and a dragon wrapped in one, it doesn't get any deadlier than that :P
oh yeah and its Sand Veil ability makes it a little tougher to hit under a Sandstorm, although that has more to do with luck than anything.