I have this game and I think it blows. I never played it online, so obviously I know I missed out on it's main purpose, but the multiplayer is horrible. One player dies, then you all have to start the mission over again. Single player isn't very fun, I just couldn't get into it. I tried a few times and each time I remembered why I thought it sucked.
I guess I'll give it another try, and really stick with it, but only when I find the time. I'm playing Skies of Arcadia: Legends right now.