I love the 2012 series. The final season actually has them team up with the 80s cartoon turtles. I'll admit that at first I was hesitant because of the 3D style, but it has grown on me.
There's some surprisingly well choreographed fight scenes, as well as some brutal moments reminiscent of the gritty b/w comics. For a show rated TV Y7 it's got some fairly adult moments.
There's a good blend of comedy, and the Turtles each feel well developed. It's clear the crew really cares about the characters and property. TMNT is a very adaptable series, and even in the comics there's quite a few alternate tellings.
So, I say it's good, but don't expect it to be the 80s cartoon, because it is a more modern telling. After the first few episodes it gains it's stride. I highly recommend it.
Side note:
Mark Caso, the original suit actor for Leonardo in the 80s TMNT movie liked my sketch on Instagram, so that was pretty cool!