It was closer to the comic in tone, but still had stuff the comic didn't (no story of Leonardo getting his ass handed to him by Shredder and about 50 foot soldiers, for one thing) and was still kiddied down a bit. It was better than what had come previously, but still not quite there.
As for GH being a sidekick to Kato... Well, let's just say that's a holdover from Bruce Lee being the original Kato on the TV series. Hard to make that man a second fiddle to anyone (remember, he kicked Chuck Norris' ass).