Hm... I never get the TMNT films I actually want. XD Like maybe a verbatim adaptation of Mirage's City at War arc, animated entirely in black and white and in Jim Lawson's art style. Not sure if that would be rated R or just a hard PG-13 though—the way Karai impales that Foot Elite on a lamp stand was kinda graphic.
I probably wouldn't enjoy the new film. My elder brother watched the previous film, and told me point blank never to watch it—it's just too bad. XD Apparently the new film is a slight improvement over the old one, but if it's still appealing only the 1987 TV series, I'm not likely to enjoy it at all.
The 2014 film actually wasn't that bad (better than the 2007 by-the-book retired turles *shutters*). The worst parts were perv Mikey, nerd Don and a lot of clearly cut content mostly having to do with the Turtles origin which made the film appear to be a mindless action flick. The best parts were Raph fearing that he would fall behind his brothers in the future, Leo being a good leader like he was in the Mirage Comics and that the writers remembered that April is just as much as a main character as the Turles (could they have gotten a better less wooden actress, oh yeah).
In fact I firmly believe that Eric Sacks was going to be Oroku Saki reincarnate and Splinter was Hamato Yoshi reincarnate and the turles were going to be the sons reincarnate. I know it sounds crazy but the scenes with Shredder feel added.
Well, the 2007 film certainly had its weaknesses. All the turtle CGI models looked like DuckTales rejects. Way too toony—not that I didn't expect some tooniness considering the rest of that film's visual style. I've heard the comic version that Mirage Studios made was actually much better than the film, and the film was intended to be more like that, but...Hollywood studio executives happened, or something like that.
And yes, I think Eric Sacks was originally intended to be the Shredder, and his name was actually an alteration of Oroku Saki (EricSacks = Oroku Saki). I don't know why they ended up making him a separate character—maybe to avoid accusations of character whitewashing (casting characters with Caucasian actors even when it makes no sense to do so, because Hollywood producers and financers consider Caucasians more acceptable to movie-goers—yeah, it's totally racist) or something like that.