He's an exact clone of Prince Charming, only noticably smaller and faster. All of his moves have the same animations (with the exception of slams), combos included, and have the same functions. A couple of his combos seem to do about a fifth of a letter difference in Slam but it isn't even a noticeable amount. His frame data may be slightly different, I haven't checked. His combo game is absolutely incredible, able to confirm 3/4 of a Slam meter off of a jab easily, with fast shieldbreakers, multiple attacks to put the opponent in knockdown, and combos that actually link into grabs. He is one of the only characters in the game with an airdodge. If he uses swoocing and airdodging to their full effect, he becomes blisteringly fast. He is also one of the only characters with two different slams, one of which can be aimed. I've also noticed that his souper grab options seem to work better than Charming's.
Point is, if Charming is viable, I think Hook has to be viable as well. I'm actually considering picking him up as a secondary since his movement feels much more fluid to me than Charming's and I want a sword-based character in my arsenal. Then again, at this point I've used him enough and picked up enough tricks that he may as well already be my secondary, along with nearly half the cast.