I might as well lay in my .02 cents after watching the special several times. By the way, the special is on youtube.
I'll start with the bad points:
The 80's turtles and the villains were portrayed as incompetent idiots. I know the 80's show had a lot of cheesy-ness to it, but the four turtles weren't that goofy, well Michelangelo was. But Leonardo, Donatello, and Raphael had Michelangelo's laid back goofy personality. When they all went down to their lair from the elevator, they all laughed. When 03 Leonardo wanted a suggestion about how to stop the Technodrome, he looked at the 80's turtles and said besides going out for pizza. 03 Raphael said the 80's turtles can't help do anything because they don't have any brains, to which 80's Raphael said we resemble that remark, and all four 80's turtles laughed.
Sorry but the 80's turtles were never mentally challenged, well maybe Michalangelo.
It got so bad that even the 03 Mikey asked them if they're ever serious. That's saying something when the 03 Mike gets mad.
Now for Shredder and Krang. Did they decide to not fight back against the 03 Shredder and his daughter? Do they not care that their Technodrome is being turned up side down? In the 4th season episode "The Foot Soldiers Are Revoluting" Shredder and Krang don't take kindly of a new super enhanced foot soldier telling them what to do or that he's taking over the Technodrome. In fact Shredder fights the foot soldier. Also in "Revenge Of The Fly" when Baxter Stockman comes back, he and his computer alien friend take over the Technodrome and lock Shredder, Krang, Bebop, and Rocksteady in a room and Shredder wants to get out of the room and gain control of the Technodrome again. The writers for the special made Shredder and Krang a bunch of idiots.
Also, how come the the 80's Shredder didn't try to fight the 03 Shredder and his daughter? How come Krang didn't put up a forcefield around Karai when she broke into the Technodrome. Krang has done it before, especially with people like Baxter the fly. Again, the writers wanted to make the 80's villains look like buffoons.
Also at the end, Shredder and Krang say they're going to get everyone with a giggle ray? I know Shredder and Krang used all sorts of different ways to try to eliminate the turtles and take over, but a giggle ray? The writers again were telling the audience the 80's Shredder and Krang are ridiculous compared to the 03 Shredder.
03 Raphael always making remarks about the 80's turtles. He called the Technodrome a golfball on wheels, called the turtle party wagon a clown car, and called them yahoos because of having initials on their belts, and called the 80's turtles home wacky land. At one point I wanted someone to kill the 03 Raphael, just so he could shut up. Got tired of his attitude. He's like Wolverine in the X-Men.
Now the good:
It was nice to see the 80's turtles, Shredder, Krang, Rocksteady, Bebop, Splinter, April, the turtle van, the turtle blimp, channel 6 news building, the turtles lair, Irma, the Technodrome, etc.
The first room where 80's Shredder is at when the computer tells him he's in another dimension is the exact same room where viewers first see Shredder in the first episode of the 80's show.
Rocksteady and Bebop actually save the day.
The 80's turtles saying they save April at least once a day.
The classic black and white turtles. They even scared the crap out of the 03 Shredder.
And of course, 80's Raphael breaking the 4th wall on three seperate occasions. All three scenes have Hun in them trying to figure out who exactly Raphael is talking and looking to with the third time Hun actually asking why he keeps on doing that and who is he talking to. The 80's turtles and villains know they're a cartoon show where as the 03 turtles and villains haven't figured that out yet.
Overal, the writers pretty much said the 80's turtles show was a goofy series and that the turtles and Shredder and Krang can't hold a candle to the 03 turtles and 03 Shredder. That's the message I got from watching the special.