We stayed for 8 days at the Barcelo Hamilton in Es Castell. We really enjoyed the hotel, the location was pretty good (30m walk to Mahon and with busses driving often) and a lot of restaurants nearby. Es Castell was a really pretty and real Spanish village, which we really liked.
The only thing we can complain about is that there was no minibar or fridge in the room, and that the reception staff was not too talkative/helpful with us and little service-minded. We never got any indications on what to see and do even if we asked, and they always seemed to have little time to talk/give advice. Otherwise, the personnel at the restaurant was really charming, always greeting and being available for all clients.