Everyone hates the post-movie seasons, but can rarely quite articulate why. I think I can explain.
The early seasons had a clever, deadpan, "sitcommy" feel to them. Like, you know it's a children's show, but the way it's paced and staged can also appeal well enough to adults.
The newer seasons, on the other hand, feel like a typical Nick Jr. show, with plots and jokes so corny you can see them coming a mile away. Spongebob is much more effeminate and screams/cries all the time, when he only did that a few times in the old episodes. Nobody over 5 would probably watch these episodes without feeling very embarrassed.