There's a ton of stuff to like but it was the D&D references that first caught my eye - just check this episode out! Displacer cats, mimics and other Dungeon nasties.
The setting is a bizarre and post apocalyptic one - the magical kingdom of Oooo, which seems to be what the Earth(?) has become after the "Mushroom War".
Finn is a 12 year old Human who wants to become the best adventurer in the land and Jake, his faithful companion, is an awesome magical dog who can grow, shrink and party with the best of them - and he's voiced by John DiMaggio - also the voice of Bender in Futurama.
Adventure Time is now essential viewing for me and the boy, much to the wife's annoyance - not sure it appeals to her sensibilities!
The possibility of gaming Adventure Time had also occurred to me - how cool is this!