The Turtles Trial doesn't allow you t access the Offline Co-Op (may allow online, don't care yet personally.) That's a bit eh. So you can't even see how Arcade mode differs.
But for the actual game itself? A nice presentation (even if you hate the necky turtle designs), The comic panels are a nice touch in some ways, but they also feel like shortcuts to rendering certain scenes in-engine.
The Gameplay; I never relly care TOO much for AA-style fighting, but this is a nice, multiplayer/multi-character twist. It has more delay than I'd like, but that's because you're basically "queuing up actions" as oppose to "button mashing". Mashing will get you doing chains of things you don't want to do, so you really have to time your strikes.
The game offers lots of animations to make the motions somewhat believable. There's lts of cool "countered without even turning t face the enemy" style stuff going on, and the unique finishers come in a multitude of ways.
They also attempt to put life around every corner, as if they really want you to feel that the turtles are working in the backdrop of a living world. This is cool, but kind of jarring.
You can access the training dojo in the demo, which I recommend: the combat makes more sense when you can take it to the side, and experiment. I don't know what the trial for "press b while in the middle of a combo or attack" means, however; It's suppose to be a "knockdown counter", but I wasn't able to get it to work right, though I think it's a method to stop your combos from reaching finisher hits.
All in all, it feels meaty, like it has it's own identity, and like it could offer a well-developed experience, if you give it a chance. I just wonder if the initial flavor will make people want to give it a chance, or if style / perception issues will turn people away. Can't say much more, as I just played the trial myself!