Turtle Ninjas > Pirates
Certainly, this game was an awesome 2D fighting game. One of the best ones out there during that generation. Of course, as most 8-bit games, it was long and brutal. If I recall correctly, the farthest that I've gotten without cheating would be the sewers...or maybe the Technodrome. Usually gator head totally obliterates us or the long corridors in the Technodrome. Usually, I had to resort to the cheat code.
Just like any other 2D games, it quite long with lots of enemies. It's nice how the stages changes and have their own peculiar-ness. Such as when a person gets to Manhattan, some areas would break and fall downward. Take a good look at the cover art and you'll understand why.
When compared to TMNT II, I thought Konami really did well. It was polished and fun. The fighting was also improved from TMNT II to TMNT III. Fighting was really hard in TMNT II. Of course, that doesn't mean you'll let your guard down. How the fighting system improved was that it felt as if the Turtles had more moves at their dispense.
Recommendations: For those that wish for some truly good beat'em up old school game, I highly recommend TMNT III.