This show is very entertaining, even for an adult. The innuendos are the funny part. The humour is directed at children below the ages of 13, but it makes the show a great timepassing tool nonetheless.
The art style progressively gets brighter and less "eye candy" than it was in the first and second seasons. It aged like SpongeBob.
I'm a fan of this show. Each episode really has no ongoing theme except for some minor problems that can later show up randomly. That's what makes this show so entertaining to watch. Instead of clinging onto one episode, waiting for the next to see what happens, each episode begins something new.
You don't have to keep up with one plot, and issues having to be fixed and have to be drawn out into two or three episodes. You can watch an episode and still get the main plot and idea of it.