I liked it. If anything, Twilight Princess has the best replay value in the entire series; second to Ocarina, probably.
My biggest problem was with the entire Twilight Realm thing. Mass-collecting a lot of little items (the tears) shouldn't be a definite objective, rather it should be optional with benefits, like in Banjo-Kazooie. And even though the place had a cool art style, I just didn't feel anything different about being a wolf. The wolf should have been separate from Link's world entirely - the world should have been designed so the wolf would need to take a different route to what Link normally would. There was some of this, but not much. In stead, where Link could go, so could Wolf Link. Wolf Link should have been taken to completely new areas, with completely new characters (like a gang of wolves) that really defined the experience in that form.
That was my biggest problem with the game. Otherwise, Twilight Princess did a lot of good things.