My family of 5 loved the Harmony! We went the week before Christmas and had a great time. We had 2 balcony rooms (Junior suite for me, DH, and DD5) and a regular balcony room next door for DS10 and DS12. Had a blast going down the Abyss slide (much more fun than the water slides in my opinion) but I could only get my DS12 to go with me (everyone else chickened out!) Loved Wonderland restaurant for the fun quirkiness but I wouldn't recommend it unless you're an adventurous eater. (We ditched the kids and had a date night here). The food is great but strange.... Who knew I'd love raw tuna topped with a lime flavored slush covered in salmon roe?? Our favorite meal was Chef's table - by far! We had never done that before and now we'll do it on every cruise!
We watched 3D movies, hung out at the pool, watched some great shows and had so much fun! The aqua show was amazing - great diving, stomp dancing and splashing on a water/covered stage, acrobats flying onto the stage...Coolest show ever!! Grease was great and the kids watched this with us. The ice skating show was a little slow for me but we didn't have great seats so I may have been cranky about that. Comedy shows were entertaining but not fantastic (Carnival has MUCH better comedy shows, IMHO. We laugh 'til we cry on Carnival ships). But Royal kills Carnival in the other stage shows.
We ate in the main dining room most nights and I thought the food was great. I'm not a big buffet fan so we stayed far away from that. They now make you go to sinks and do a full hand wash when you enter the wind jammer (no hand sanitizer) and grown adults were having hissy fits about it. The solarium had a smaller but very nice breakfast buffet so we ate in there every day. I was doing a continuing medical education conference on board so I was in class in the mornings on sea days and met up for lunch with the family afterward. My husband would take our 5 year old to the boardwalk in the morning for face painting and riding the carousel while the older boys slept in. We bought the Royal Caribbean app (maybe $15/device for the duration of the cruise?) which allowed use to text each other (and home). It also allowed YouTube to work which my kids loved (but was much cheaper than the whole internet package.) I love the bigger ships and love the Oasis Class. The pool area isn't packed like on other ships (because there is just so much darn stuff to do during the day!) We have also been on the Oasis but loved all the slides on the Harmony so I'd probably pick that ship again over Oasis.
Royal also allows you to bring 2 bottles of wine on board per stateroom (without a corkage fee) so we brought 4 bottles on board. Enough for our nightly dinners - no drink package needed. We did buy a package of 10 drinks about midway through the cruise and bought the soda package for everyone in the family. My kids thought it was their favorite ship so far (4th cruise for them). We're cruising to Alaska with NCL this summer (from Vancouver to Seward, inside passage with Glacier Bay) - hoping they like this next cruise as much as Harmony! Have fun planning!