I got it at launch in England (Had it for ages) and I've got a tournament tomorrow
I LOVE IT
I think the 1 player is demanding, but ultimately rewarding (because you NEED Stormship Stadium to harness your skills, it tilts, the lightning, every goal is a battle). I completed 1 player mode with little difficulty.
Multiplayer is incredible. Online works surprisingly well. I love the ranking and season system (last week I beat Europe's rank #5 5-1

).
Admittedly there are some problems. Unskippable initial cutscenes online for instance (I think Water's blowing some huge smoke when he says "You go right into playing, no countdown" - there's a 15 second cutscene showing all your teammates for every match

).
And there is an awful amount of luck involved. If you hate the idea of other variables out of your control stopping you playing, you'd hate this game. Items are given for charged shots you fire, or for fouls you've received. But the only variable on what items you get is the scoreline. If it's 0-0 for instance, you might feel short changed when your foe gets his/her super ability just for shooting a charged one inside the half way line.
However, as a poker player, I look over the luck aspect. There's an amount of skill involved (and for those saying that 1 player is too hard, you seriously need practice, and that's the truth) and love this game for it. It's casual multiplayer, but hardcore depths make it appealing to many.