The ending is the most talked-about part of this game, and it's understandable, because the rest of it is pretty unremarkable. It's impossible to discuss without spoilers, but if you've ever read The Dark Tower series of novels, it's vaguely similar to that ending. I get what they were going for, and I appreciate it on a certain level, but I think they went a little too far with it, where several plot threads/characters are not given a good resolution (or any at all, in some cases).

As for the game itself, it's fine, I would place it above Tales (my least favourite) and below Escape.
The puzzles are uniformly too easy, even playing on the supposed hard mode.
Striking a balance between this and moon logic is a notoriously difficult task in adventure games. Overall I think the Monkey Island series has handled it fairly well, the majority of its puzzles are logical at least in retrospect.
But I still think Return fell too hard on the latter end of the spectrum. A little more complexity would have been appreciated.

The art style was a (incandescent) talking about when the game was first revealed. I didn't care for it at the time either, although it grew on me significantly once I actually played the game. I never loved it, but it's inoffensive enough. I find it kind of charming that the Monkey Island series has no consistent visual style, it helps each entry to feel unique.

Overall, it's fine. Not great, but nothing to get upset about.