I don't love it but I don't hate it either. It's mostly random episodes and there isn't really a series storyline. But my favorite episode is when Finn and Jake enter that bandit city and everyone is evil and Finn tries to keep clean but eventually succumbs. =D
I used to think adventure was just okay or sometimes bad. But then I found out that they lived in a post apocalyptic world and I thought the show was awesome. They constantly refer back to the fact that the world ended. There are storms of knives, there are things that are getting reinvented (like rocketships), there are the humans who live underground but evolved to breathe water (except for one?) I love post apocalyptic settings for reasons even I'm unaware of, and I think it's even better that they found a way to sneak something that dark onto cartoonnetwork.