Let's see we've had a season of angsty Leo, check! Raph's our default angsty turtle, check! And now it's only fair to make it Donnie's turn right? Look out, Mikey, you're next.
I'm still getting used to the new animation style at this point (the new pupils still don't look right to me), but the episode itself was well done. The way Don's new behavior is introduced is pretty well done, too. It's not simply there for the heck of it, but watch out, he WILL repeat that it's "all [his] fault", I think, three times in this episode. It just gets a little redundant. I'm just happy to have the turtles back in present day New York. I always loved the episodes that were more realistic and less sci-fi or fantasy-based.
This new villain also looks like a challenging new match for the turtles, too.