You have to ask yourself what exactly qualifies for a good movie, and when it comes to comic book films, quantifying greatness can even be a harder task.
For one thing, you would not think a film about four mutant teenage turtles would qualify for a "great film." But, that is our imagination isn't it? Four mutant turtles? Radioactive spiders? Men driven by physiological trauma to risk their lives and dress up like bats? A seemingly phantom like figure carried by once loving memory of his future wife lead by a mystical crow?
Our collective imagination runs deep. If one were to bring up the argument that "four mutant turtles" is ludicrous, well, I don't want to know you. You're shortsighted and bare mind void of imagination is enough to tell me you're heart is seemingly rotten.
Dismantling the argument that condemning one form of imagination is not a valid argument for a film not being great, consider the following of what makes a great film:
The collective occurrence of good acting, music, plot, and of course, characterization. Well, what makes a good "comic" film, pray tell? Many would agree, the adherence or "faithfulness" to source material brought together with what makes a great film, right?
When I first saw TMNT 1990, sitting there in the theater, I felt like I was having an out of body experience with joy. The TMNT were on every kid's mind, it seemed, back then. It was a joy to see them come alive, on the screen, fighting their nemesis Shredder, with the aid of their human friend, April.
The movie qualifies for the best comic to film adaptation because of many things.
For one, the filmmakers, and director knew a very important thing about their audience. They knew parents would most indefinitely have to bring their kids, the targeted audience, to this movie. That in mind, they knew when to hold back the damn cheese. You know what I mean. The film almost never insults the audiences intelligence. It is gritty, dark, and surprisingly violent!
Just like the original comics! Back to the whole source material! Wow! What a concept!
To add to that, the characterization of Leonardo and Raphael were handled quite well. This film was about four brothers, in search of their lost father, and amongst that journey, discovering things about themselves, with fun action, good acting, and minimum cheese. Some of the things Splinter says, are so profound, you would have thought it was a different type of film.
Everyone could relate to Raphael's inner turmoil of anger, and when the calm and wise father advises him that his family is there for him, in a well acted for puppets and NON-CHEESY sort of way, there's an immediate connection, turtle or human or what have you.
Breaking down the simple elements of having fun, and keeping things grounded, while at the same time not contriving situations and acting, goes a long way.
You can nitpick many things about this film, I'm sure. But there's no denying it was made with the intention of "Let's get this puppy done right." The independent film nature of the project was probably the best thing to happen to TMNT.
Some more elements of greatness. April O'Neil was spot on. The nemesis, or The Shredder, having an close past with the heroes and their father, was a bad-ass. The musical score of the film is engaging, especially during the final fight. The acting, especially for the turtles, guys in costumes and puppeteers on the side lines, are exceptional!
Consider the end scene, when Leonardo is grasping for dear hope with Shredder's weapon at his throat, Michaelangelo and Donatello look to the respectable and older brother left, Raphael, to whether they should toss their weapons or not.
Little things like this, showing the foresight and thought and consideration for a property that had been alive for only 6 years (1984 comic debut) was inspiring.
In the end, the dark, gritty nature of TMNT, along with element that this film stands very well today, despite it's cultural references, while adhering to the collective band of what makes a great film and it's uncanny respect for the source material while instilling only some of the elements of the cartoon, in my mind, is the best comic to film adaption to date. Hands down.
This is coming from more of a Spider-Man fan, than turtles fan. I wanted Spider-Man to be so great, but Sam Raimi's lack of foresight and adamant nature to instill so much cheese in the franchise, while making Peter Parker a mute no personality shadow of himself, well, has prompted my encouragement for the forthcoming reboot.
The only thing that sickens me is that there is no special edition of this film with deleted footage or documentaries. Yeah, there is some bull-crap German version, but how does that help us here in the US. I can't wait for a special edition on Blu Ray with all the bells and whistles, this under-appreciated film most certainly deserves.