Fuck Cartoon Network on that one.

Well, to be honest, Flap Jack was running out of ideas. You can only go look for Candy Island so many times. It's a self-limiting show. They're effectively stuck on a harbor island, with a few cast of characters, and a few possible adventures. Dunno, I love Flap Jack to death, but I also kind of feel like it might have had it's run.

Adventure Time is promising, and this Regular Show looks like it might end up delivering. Give it a few episodes before we judge it. It's got some big boots to fill, and it'll probably take them an episode or two, hopefully, to start nailing down their formula.

One. They were not running out of Ideas. There are tons of adventures to be had.
Two. They live on Stormalong, not Harbor Island.

Flapjack and Adventure Time both have theme songs.

It has a theme song! It was composed by Mark Mothersbaugh.

When did it start being good again?

Why is every 'wacky' cartoon that comes out now labelled a Spongebob clone? A shit-ton of animators worked on Spongebob, so naturally their aesthetic touch carries over into shows they created themselves.

Not as good as the pilot, but +3 stars for the cartoon and +1 for the Adult Swim guys taking over Cartoon Network and greenlighting shows that are basically a gateway drug for Adult Swim.