It's kind of RPG, in that you have battles and find/win money and then buy new/upgraded weapons and armour, and level up your character. But the main part of the game is basically a series of battles, where you fight a series of 'boss' type characters with swords. Learning to parry, dodge and block, and how to do the combos when attacking is a big part of it.
Neither of those are really my thing, but I really enjoyed the game - it's easily the most played game on my iphone. And yes, the graphics are the best you'll find on the iphone 4 I think (or ipad, it's especially good on ipad2).