Though you can finish Unlimited Adventure in roughly 30 hours, the game is much more enjoyable (and less frustrating) if you take the time to skill up your characters and collect items for upgrades. For those fanatic collect-a-thon types, 1UP can easily see the game taking upwards of 60 hours to max out all characters and skills. And that's really what it comes down to.
While fans of the series will love the dialogue and humor between the characters (as well as fighting against some of the series' most badass opponents -- Mihawk, anyone?), whether you enjoy the game comes down to how much tolerance you have for skill grinding, item gathering, and repetitive -- though admittedly cool-looking -- combat. Don't get 1UP wrong -- there's nothing intrinsically wrong with this. After all, those are all parts of why MMOs are popular time-sinks. Unlimited Adventure isn't a quick journey by any means, but series fans will certainly find the ride that much smoother.