The online play is where the game will stand or fall. Numbers aren't huge at the moment, but if you can manage to find others around the same skill level as you – rather than those of immense ability who'll club you out of the ground with each ball – then you should have a great time, as the underlying mechanics are solid.
However, it's inevitable that some bastards will find exploits and use them to grind out win after win. If Mindstorm can deal with this when it happens, they could have a sleeper hit on their hands. If only it didn't look like such a dog's dinner.