The Next Mutation suits were much better than these (even though they're inferior rubber suits to the film ones). But The Christmas special and Next Mutation are bad on different levels. The low budget and ugly look of the Christmas special is part of why it's terrible, no question. The real stinkfest is the horrible "turtlized" lyrics they threw into the public domain Christmas music. No, scratch that... the fact that whoever wrote this pretty much said "all the turtles are Michelangelo from the 80's series and all they care about is pizza, comics, and extreme stuff." A) look at what they give Splinter, and the gifts they consider and B) the lyrics of their version of 12 Days of Christmas. All the characters have been written generically and have been Flanderized down to a didn't do the research shallow parody version of themselves.
As for Next Mutation... I really felt betrayed by that show. It started off quite good, and as expected for a live action version of the characters. Then they tossed in Mary Sue-elangelo due to pressure from the network, and the show went downhill fast. The suits weren't movie quality, but the show had such an insane budget that it broke the show. Next Mutation wasn't canceled due to low ratings. Not at all. The budget was just intense. And unlike the other Saban shows at the time, they couldn't fudge the budget with footage from Japanese series. They had to do their own action scenes. And the worst part was, the second season sounded like a complete turn around. A death in the family (I hope it was Venus), Casey and April were supposed to make the scene. They even considered going back to animation, but it just disappeared from there.