Also KH is more likely to get cheaper than a Nintendo product.
Exactly right. In a few years Dream Drop will be $15, while Uprising might be $35 if you're lucky.
Really though, although I've heard excellent things about KH3D, I've heard them mostly from big fans of KH. One of my buddies thinks it's the best Kingdom Hearts yet. But Kid Icarus is just an unbelievably great game... though maybe if you have big hands or something you should try it out first.