[onepiece]

If you are looking for different setting, story and the like, you will found mostly different playing styles (champion of the arena, a redone campaign and defender of the crown).

The campaign (March of the Orcs) is mostly the same from AP, plus the giftbag, some recolored units, more items and spells (bases on the 4 rage spirits from The Legend) and the like. This one doesn't add very much (compared to AP)

Defender of the Crown is a set of battles in special arenas (enemy area is full of walls for protection or has a barracks that summons units) and you gain levels extremely fast (2-4 per battle) and is for hardcore battles.

Champion of the Arena is a mini campaign in which you do assasin mission (kill heroes) and do battles on small areas (like the campaign with no island and small areas). I havne't played this one very much and don't know the rest. Look for the official thread on this one for more info.

The editor (for modding and replay value)

And the original campaign (XD)

Conclusion: From your answer I'll say you wait a little until it gets cheaper. The campaign isn't much improved (at least in the beginning) but has some nice additions. I say you wait a little time and then give it a chance.

P.S: I miss some of the "legend" jokes and funny stories and things (the train for example or the submarine) plus the giant turtle and the big settings (land of the dead!!). I think AP lacks that "energy" and setting and moments but overwhelms it in terms of gameplay.