We decided to try "one of the biggest ships in the world" in Allure of the Seas and it sure was big. Too big for my taste as whenever you went to any of the popular areas (Promenade, Casino, Pool Deck, buffet) you were surrounded by people. It actually felt more crowded than if it was a smaller ship.
We went on with our almost 3 year old son and extended family. If you take young kids, you'll need to have a stroller because it takes a bit of walking to get anywhere and little legs get tired quickly. The kids pool area was okay but a bit disappointing especially when we docked alongside the Liberty of the Seas which had a FANTASTIC looking water park for kids. The play area was okay and was a nice place to take him to run off steam were he wouldn't (literally) run into other guests.
The ship itself was beginning to look a little worn down. Peeling wallpaper, broken chairs scattered around and pillows that felt like they hadn't been changed out since the ship debut were only a few of the things that stuck out.