A lot better than some people think or seem to remember. Sure, it's not the best of the series, but not bad either. Some of the puzzles are a bit harsh and the Monkey fighting system gets a bit annoying. The controls take some time to get used to and there are a couple of plotholes, that I'd rather not spoil.
On the plus side, we see the return of some of our favorite characters, as well as the introduction of some new ones like I. Cheese, Pegnose Pete, Ozzy Mandrill and even that lovable rascal Charles L. Charles. The backgrounds are pre-rendered 3D images and they still look great, though I miss the gorgeous Curse of Monkey Island backgrounds. The character models are a bit boxy, but the game is from the same era as Grim Fandango, so it's understandable. The writing is pretty funny and the voicework is stellar, with Dominic Armato returning for the role. The music is pretty great, which is no surprise - this is Monkey Island after all. The game itself is a bit less serious, feeling more like a Disneyland tour than an actual pirate game, but if you are in the mood for a fun adventure, you'd get one.
If you are a Monkey Island fan or an adventure game fan in general, you should try this game.