In a channel filled with many shells of older, better cartoons, TMNT 2012 has filled the void many old Nickelodeon fans have suffered. The show is a loose spin-off of the 1987 show by the Murakami Wolf Productions. (There is a minor character named Murakami-san, which is a homage to him.) It's actually the only reason I go to Nick, besides some hidden gems such as Legends of Korra. However, the show does have its flaws.
Let's focus on the good. The character development has been amazing. Raphael with anger issues has grown into a slightly more compassionate person who defends his family. Leonardo has grown into a deeper character than previous incarnations. Donatello had several episodes for his development, which include Metalhead and April. Mikey seems to be the only one who hasn't really developed because of his role as the plucky comic relief.
While it is a CGI show, the animation is bright and beautiful. You can see many references to the previous incarnations and there are anime- esque moments. The dialogue is quite funny. (Master Splinter's humor is quite blunt and dry. He even called Timothy a doofus despite his immense vocabulary.)
The only bad thing is the slow pacing, how April is treated within the universe, Mikey's pure ignorance, and Donatello's stalkerish behavior. Animation-wise, the ambiance is poor. NYC should be hustling and bustling with a diverse community. Hopefully, these things will be fixed as the seasons go on.
It is quite violent. However, there is no blood or gore. Language is minimal. Insults and quips are normally directed at villians. When the TMNT become too proud, they often have their butts served to them. Consumerism would be your biggest problem as there is a whole line of toys from Playmates. The only sexy thing is Donatello's crush on April, which can range from harmless to stalkerish. However, it can teach children to love beyond looks.
I honestly disagree with CSM here. The violences does not overshadow the positive messages, and there are always consequences. Ex. When the boys become too prideful about their efforts, a stronger villain normally teaches them. Ex. Leonardo learned he could not be overly trusting of some people, such as Karai. If an atrocity like Robot and Monster could earn four stars, TMNT can earn five.
P.S: It seems as if CSM has a vendetta against the turtles. The only turtle-related thing that garnered four stars was the rooftop app. I'd suggest going onto IMDB, Tumblr, or other places for un-biased reviews written by real Shellheads. Cowabunga, dudes!