Pros and Cons are very subjective. Here's an example:
Casino. DCL doesn't have one. For us, that is a HUGE pro! For others, they see that as a con.
Entertainment. DCL has family entertainment that while stellar in quality may at times have a bit of a juvenile subplot. Con for some. Mostly pro for us! (I'm so over high kicks and thongs on the main stage with vegas style cruising.)
Smoking policy. DCL doesn't allow smoking on balconies anymore (neither does X, RCI or Princess) so for some, a BIG pro! For others, a con.
Dining Rooms. DCL has lively environments with interactive animation. It was a major major plus plus pro for us! We missed Turtle Talk at Epcot the day before and were delighted when it came to our dining room. Others see Animator's as loud and distracting. Pros for us! Cons for others.
I don't think the kids are really a con, there are so many activities for them on the island and on ship, and so many adult areas, this personally was fine for us. We enjoyed them at Family Karaoke and Fiesta Salsa dancing (SO funny!) and then we could go to our veranda or adult areas whenever we wanted. I suppose some would see this as a con, but cruising CCL and RCI, there are just about as many kids, probably less supervised (especially in the evening since the clubs start charging after a certain time and parents don't want to pay, so they roam around.)
For us, the characters around are a MAJOR pro! We never have time in the parks to pose for pictures. This time, we got photos with 4 princesses and got to talk to them. We have no kids and are in our 30s. Yeah. we like princesses. If this is a con for you, they are fairly easy to avoid since they aren't as much 'in your face'. You will see them in photo areas and here and there, but its not like a pixie parade all the time.
To me, the dining was a major pro. I'm sick of the banquet lasagna style of other cruise lines and found the dining mostly interesting with a few draw backs. The specialty desserts consist of mainly sundaes (pretty good though!) and a few winners like Grand Marnier Souffle. I enjoyed the different root vegetable pairings and beautiful presentation, LOVED the seafood (lobster ravioli, scallops, escargot, sea bass) and some nice duck and lamb choices. Not everything was cooked perfectly but it was good. There were a few low notes (square pressed hashbrown is not impressing my husband) but Cabana's buffet is definitely the best breakfast buffet I have EVER had. Some people find DCL food to be too boring, and others find it to be too fancy! So... that's a tough one. Food is really subjective. I'll say personally to me, it was much more interesting than the CCL food (which is actually really good) but I may just be sick of their same menu year after year. I think DCL had greener, yummier salads (including goat cheese! Yummy!)
There is only PROs to me about
Castaway Cay. Only Con being if you couldn't dock there that day (it happens occasionally.) We enjoyed the food, the fruit stand was AMAZING, and there are different ice cream flavors. We enjoyed the snorkeling, but you have to really swim out VERY VERY far to see anything. If you dont give up, you will be rewarded. There were thousands of fish out there. Not the brightest colors I've ever seen, but probably one of the highest quantities I can remember seeing in one place. (Like a giant column of hundred and hundreds of fish all together!) The volleyball is fun! The whole island is a blast. It's like going to a 5th Disney World park only you can help yourself to food and drinks the entire time. (Which felt odd to me at first!) Never made it to the adult areas even though we had no kids with us. That's my goal next.
The staterooms, well, I can only see that being PROs too. Even if you get the basic interior cheap room, you get a full bathtub. This is amazing to me. Other cruise lines give you a small shower curtain with a metal bar at the bottom. Some NCL has a toilet IN the shower?! At least that's what the photos looked like?! It's nearly impossible for me to balance all my conditioner (long mermaid hair) and not drop it on my feet constantly, and having a tub is SO nice for shaving too. I have heard some on RCI say they have to 'get creative'. DCL has the best bathrooms I have cruised with (basing off of interior standard rooms. obviously if you go up the line, you can get better on any cruise ship.) so right away, you are getting a better value for your standard inside room. Deluxe is even better since they have totally split up bathrooms and are ideal for families. Privacy is the best I've seen on DCL. But the thought of fitting a couch in my interior rooms on other lines is funny. They also have a great amount of space for storage. They know families are traveling and this is reflected in their rooms. Even if you dont have a family, its still appreciated. (One CON, the couch bed is awful, at least on the Dream. The bunk is MUCH more comfortable, so a pro there if you have a 4 person room and need 3 people sleeping.)
Another HUGE pro for rooms is being able to stock them with whatever beverages you would like in whatever quantity you can carry on, and that includes island purchases as well. We enjoyed our own margaritas (not so sugary!) and a nice glass of wine or some rum when we wanted to.
Here are some CONS for us. Pizza and buffets closed at midnight. The only food option was room service at that time, which is free, but it was over a 45 min wait that day so we said never mind. In reality, we didn't need to eat that late anyway. I'll just make sure I go get pizza at 11:30 if I really want something. The hot tubs also close at midnight, but I have experienced that on other cruise lines too. While there was some stuff going on in the adult areas, the consensus is that the ships get pretty quiet after midnight. We just found some awesome CMs to hang out with and chat with and then went back to our rooms and watched the moves On Demand.
I guess that's all I can think of for now. For me, it's going to be very, very hard to cruise any other line for a while. Even if I have to cruise shorter times (4 days vs 7), our 3 day showed us that the caliber of what they offer makes for a much more enjoyable trip. I MAJOR MAJOr pro for me was not personally being pestered constantly for drink sales (although I know CMs can differ) and we were even given BOGO free. Also not having so many hecklers for photographers. "Let me take your picture!" Sheesh. And by far, probably my most favorite would be bingo not being so much in your face. 'Buy Bingo!' Ugh. Its one thing if you want to go to a lounge to play, that's your business. Its another if you make me get to the theater and then have to sit through a bingo game and I lose my seat if I leave. Talk about a captive audience. That's the major differences I can see from having a few lines to compare.
Hope it's helpful!
Nothing beats the "Suite Life". 
