These are just my random thoughts in no particular order:
Getting on the ship was very easy. Just took a few minutes. They have characters in the lobby for pics so my 3 yr old was entertained while we waited. Max 15 minute line to check in. Somehow, Disney figured out who we were and matched our pics with Mickey in the lobby with our stateroom #, BEFORE we were even checked in! Face recognition technology??
I would recommend against registering children for youth activities in the embarkation lobby. Wait til you get onboard. Line is too long at the cruise terminal.
They try to stagger embarkation by "groups" that you get assigned to when you check in. You can generally ignore this and get onboard early, but keep in mind that before 130pm your stateroom will NOT be ready (they are even roped off to prevent folks from coming in) so be prepared for a wait. It doesn't do you much good to get on board before 1:30 if you have a 3 yr old who needs a nap! I think the pools etc. were open so bring a swimsuit in your carryon.
Oceaneer Club and Lab for kids was GREAT! My son got to do "Toy Story Boot Camp" with the "Army Man", and other activities (singalongs, treasure hunts, etc.), and didn't want to leave. You can leave your child there and rest assured he will have a good time. It's secured and gated-off, and the kids have electronic wristbands. No one except a parent or authorized person can pick up your kid and they have to know the password to enter and leave. They even feed your kid lunch and dinner there. (But they don't keep track of who eats what, so we couldn't figure out if our son actually ate anything)
Our child didn't do well in the formal sit-down dinners which take 1.5 hours minimum. So we sent him to the Oceaneer Club during dinner and we enjoyed ourselves and got to take our time.
I also liked the Wave Phones (handsets), where you can call another member in your party with the other handset and coordinate meetups and activities. Oceaneer Club will also text you for pickup if your child wants to leave.
The food was good, not spectacular. I'm used to Celebrity's spread and this was a step below that. Certainly not bad.
The shows were very well done. My son liked them all except the "Disney Villains" which scared him and we had to leave. A disclaimer "this show may scare younger kids" might have helped. They tell you "don't save seats" but this isn't enforced. Have someone at 815 get seats for all your party for an 830 show, etc.
All of the servers and crew were great and very friendly.
Note: the ship will be VERY crowded no matter when you go. We went during the school year and thought we would get a reprieve. Nope. 3,996 of your closest friends are always on board. The at-sea day was especially crazy at the pools. It's better to enjoy the pools during a port day when people get off the ship.
There are characters onboard, we were disappointed that there weren't more, especially on the last day. Be prepared to wait 15-20 minutes for a picture. This is because the staff will accommodate several pics for a family and will even take pics with family cameras too, which I appreciate. Just takes longer that way.
Pirate night onboard was a blast and it helped that our son is obsessed with anything pirate.
The room itself was good. 200 sq ft and well appointed. Beds were plush and comfortable. Our son loved the upper bunk that came out of the ceiling. The bath (yes, there's a small bathtub) was great for nighttime bathing for our child. The room is separated by a curtain so families can have their separate areas. The window also had a good curtain that blocked all the light. They even have a nightlight for kids.
Free ice cream and sodas were a nice touch.
Pictures were kind of expensive ($15-20 per).
Word to the (un)wise - if your child is under 42 inches tall, DO *NOT* TAKE THEM UP TO THE AQUADUCK (WATERSLIDE) ENTRANCE! They WILL be turned away, there are NO exceptions to this rule (not even for cuteness or standing on tippy-toes), and there WILL be tears and an ear-splitting meltdown if your kid can't get on. Trust me on this.
Disembarkation was also a breeze, I would recommend waiting despite all the panic they try to infuse in you about getting off the ship ASAP. Don't go to the "Assigned Breakfast" (ours was at 6:45!) but sleep in (a bit), get a meal at the aft dining on Deck 11 at 8:29 (they close at 8:30) and WAIT. Take your time. Chill. Relax. No rush. There are 3,996 ppl ahead of you.
Overall, very enjoyable and we will cruise Disney again for sure.