I don't know where to start with this. The list of bad things is kilometric.
1- Kid Bruce is ridiculous and the worst element of the series. He doesn't "look" like a possible Bruce Wayne. He becomes a detective and a vigilante in his (barely) teen years, meeting all the infamous villains DECADES before he would become Batman (LMAO). That's just super-lame.
The real Bruce Wayne just trained for years, years, years outside Gotham City, under fake identities. Having a weird-looking, skinny and untrained kid facing the "future" Batman villains is the dumbest idea ever conceived in the world.
2- All the villains look and feel CAMPY as hell. The acting is atrocious. The 1966 Batman show villains were far more menacing and believable.
3- They totally messed up the Joker with the contrived Valeska twins story.
4- Having the Batman: No Man's Land in the last season is a HORRID concept which doesn't make sense.
Basically, the adult Batman is useless. Bruce Wayne already saved the day (with Alfred turned into a superhero) when he was a kid.
This show is the absolute BOTTOM. The 1966 Batman show is a masterpiece that destroys this all over the map.