It's an online game. Same as the weak campaigns in CoD and BF3 etc. I'm sure there will be enough people online to make it playable, maybe not for the more casual fan (I mean in terms of someone not putting loads of time to learn the game), but for people who really want to get in to it.
At around £15, even if someone only gets a few months out of it, it's pretty good value to me. I agree that the online focus is a risk given the relative low sales of Platinum's games, but the single player is shite on loads of games that are well reviewed, and if people don't want to play it, it doesn't become a poor game - it might not be a worthwhile purchase however, which is fair enough. Relatively few people bought Vanquish and Bayonetta and they're two of my fave games this gen.
Online will be full of high ranked players, because it's not out here until today. Once the non importing EU players get in to it (who haven't had six months to level up), I'm sure it will become more accessible. Still this is only one person's opinion, I just never seem to agree with CVG's when it comes to games like 'these' - they're too in awe of bombast style AAA games. EG, Destructoid and Game Central I generally agree with, and they've all reviewed it very positively.
I'm on 360 too MrP, I'm not sure if I've got you on my friend list? Feel free to add me if you want!