It does seem short so far but that shouldn't warrant low scores. The fighting isn't that bad, I mean it's no Bayo but still decent. My problems so far has been the frantic nature of encounters. It's made more for co-op probably. When there are a few Foot on screen and all Turtles are bundling in, can hardly make out what's happening. I've got command on "all out" so I'll try changing that and see.
the main issue i noticed is that it's completely built for 4 player coop. Some of the bosses and stages on harder difficulties are more or less impossible by yourself. that and some of the levels seem to run on a random event generator, i've only seen the out of control car on the first stage once for example.
it's a bit low budget in some places but it's a sound re-imagining of the 90s arcade games, with quite a lot of technical stuff to be discovered (jump/shell cancelling, command specials etc)