Hmmm, well I have mixed thoughts on the subject due to my opinion on the source material.
Years ago I really liked the "Teenage Mutant Ninja Turtles" when they were in the black and white comic form, and the storylines while including humor were fairly serious. This was at a time when the comics code was dying, and one of the things that made TMNT cool was how the silliness was meshed so well with the grit and brutality. It could be said that like "The Punisher" at the time, TMNT was an analysis of comics as a whole on some levels, and also a criticism-in print of both publication standards of the time, and the conventions brought into comics themselves to try and work within those limitations... like the time honored "code against killing".
Oddly, maybe it's that I grew up too fast, or at least my tastes in fantasy did, but when 1990 rolled around I was 15. I was also less than impressed by the desician of Eastman and Laird to basically sell out to Archie Comics, and what they did with the franchise. The characters were greatly changed, and the tone was modified on a lot of levels to turn it into exactly the kind of politically correct "kiddified" comic that it set out to mock/turn away from to begin with. TMNT was never exactly a blood drenched book, but it didn't shy away from such things when appropriate. However with the change of sponsorship you would no longer even see the lethal connection of a weapon. Rather than the insersion of humor and silliness in to what were presented as some pretty serious situations, you saw the entire thriving on total absurdity.
To me what I guess kind of ruined The Turtles, despite oddly enough watching, was the TV show where they had this giant orange van, painted with turtle shells, that says "Teenage Mutant Ninja Turtles" on the side, and is apparently loaded with death rays hanging off the sides... which nobody noticed as they drove it around. Yet somehow despite this monstrosity that was a shameless toy commercial, they still somehow had to hide in the sewers? They didn't even bother to keep the logic of the series consistant and for me I guess "To The Turtle Van" more or less defined what was wrong.
Don't get me wrong, I'm a big fan of Kevin Eastman (hey he even married Julie Strain for a while!) and Peter Laird... BUT I did not like the way they sold out this paticular creation, despite their differances.
The point of this rant is that I'm not really sure what Michael Bay could do to the Ninja Turtles that hasn't already been done. Hardly anyone knows the characters I was originally fond of, and the cartoon/archie comics version was such a satire that I don't think it's possible to ruin it... I mean at one point they had the characters turning into mutant "Hulk turtles" if I remember (very late in the evolution of one version of the show) and even introduced a female turtle into the series due to attacks about political correctness.
With "The Transformers" the shows WERE glorified toy commercials, and they were written for young children, but there was a fairly good overall plotline. I say fairly good, because we're dealing with something on the level of passable pulp sci-fi, not "OMG, someone start tossing out the awards". There are certain standards, and expectations for what characters should be like, how they should behave, and of course what themses the storyline is supposed to focus on.
With TMNT, they already destroyed it to the "we'll do anything for a gag" level, the characterization except for "Kowabunga" and "oh boy, Pizza", is more or less non-existant. The bad guys themselves are more of a running joke than a credible threat in most cases (I mean honestly, have Beebop and Rock Steady ever won a fight without massively extenuating circumstances?... they don't even do a decent job of at least ACTING like they could be formidible. I mean sure, Megatron lost in pretty much every episode, but at least he was written well enough where he was a credible badass... in the cartoons you couldn't even give Shredder much credit after a while.... in the comics they managed to keep him cool by killing him off when it was appropriate, instead of dusting him off for a masochistic beat down every 30 minutes).
Alright, enough rambling.
Bottom line here is that while I guess I can feel for the fans, I'm not sure if this is a franchise that can be ruined. Nothing I can think of that Michael Bay could do, could possibly be worse than some of the stuff they did in the TV series, especially when it lingered on long after it's time.
Even if you don't know the original comics, I think a lot of fans might be a bit suprised if they were to sit down and actually think on this one.
