I haven't been yet but I have friends living in the area and they highly recommend Ile des Pins.

Somebody here on FR, a regular poster on the luxury subforum, mentioned that Ile des Pins was the most beautiful island he ever visited (and he had seen Bora Bora and the likes). Can't retrieve that post but I remember it and added IdP to my list because of that post.

So I would never ever skip LM IdP!