The Harmony of the Seas is a very family friendly ship with lots of activities for cruisers of all ages. The water slides are thrilling though the Ultimate Abyss dry slide was a little disappointing - I think I was too tall (6'2"). The Adventure Ocean "kids camp" was a great option and my four year old daughter enjoyed spending time their with other kids she met on ship.
Our cabin, a superior ocean view stateroom with balcony, was nice and comfortable and the balcony was spacious.
My least favorite aspects of the cruise were the size of the pools (very small) and the crowds on sea days. It was difficult and sometimes impossible to find chairs around any of the pools and in the afternoon, the pools were very crowded, at some points people almost shoulder to shoulder in the water. The Windjammer dining room was also extremely crowded, especially on port days just before disembarking - again, very difficult if not impossible to find a table at some points.