Well here's a few reasons why I don't think it deserves to be criticised that much:
* The male lead was a total failure, I admit, but it didn't really seem that concerned with him. He was treated as nothing more than a POV to look at the girls and the island. The worst harem shows are the ones that try to make something out of their lead. Harem lead characters are fucking failures by default since they seem to have a contractual obligation to not only be total virgins but to also be more awkward around girls than a 50 year old virgin priest with Aspergers,
* From what I've seen, it didn't take itself seriously at all and was just about "hey what a nice island and what nice girls". So much anime tries to rise above its actual nature only to flop horribly. This was just cheap fun and it knew it.
* The girls didn't seem to actually fall in love with the main guy (main woman aside) but rather had a jokey, psycho desire to be with him. It was nice to see that, rather than all these hot women inexplicably fall in love with some otaku failure.