I think these designs look cool, even if they aren't sensible in a functional way. I like Shredder's look.
The original cartoon I loved so much as a kid had MAJOR changes from the comic book that inspired it, the 1st movie was more similar to the comic but had its own changes from both the comic and cartoon, the comic has changed publishers and timelines/continuities quite a few times, every few years there's a new TMNT series that has nothing to do with the previous series... is it really such a big deal that this Michael Bay version is really just that, another version? That's all it is.
Now the 1st Transformers movie was pretty decent before the sequels dragged the overall franchise down. Who knows, this new TMNT might be decent as well, just like the 1st TMNT movie was (and despite it's goofiness, I still like it and enjoy it's rather semi-serious approach)...but let's not act like Secret of the Ooze and Turtles in Time were good films...maybe interesting, and maybe we ate it up at the time and feel nostalgia for those films now, but good films they are not. Definitely room for improvement, or at least room for something else.
I only managed to get 2 of the TMNT comiquettes before the prices went up. If this movie is bad and these get made, I'd probably skip and still hope for comic styled PFs.