Though I only saw a fraction of the first episode, I can confirm without hesitation that this is a Monkey Island game. The jokes are Monkey Island jokes. The situations are Monkey Island situations. I laughed more during this demo than I have in any single adventure game (or episode) I’ve played in the last few years.Update: Gamespot preview, with obligatory (somewhat minor) spoiler warning.
Update: Dave Grossman is interviewed about Monkey Island 6 (that's what they're calling it). On a personal level, I do hope they make the (mentioned-in-passing) a Monkey Island 5 in the Curse of Monkey Island/Vampyre Story vein, but adjust the art style accordingly. I love Telltale's work, and am very excited for Monkey Island, but personally am not sure if the Telltale Engine is right for this particular franchise.