I've only been on one NCL cruise (though our second begins in a little over a week). You will probably get a lot of differing opinions, but our experience was extremely positive. We found the service to be very comparable to Disney. The staff was friendly and professional and we enjoyed interacting with them. We found the food to be much better than Disney. Though, full disclaimer, we've never been huge fans of Disney's food. YMMV. One thing to be aware of on NCL is that they utilize the Freestyle dining concept. You won't have set dining times, tables, etc. You do need to make reservations at times - especially for the specialty restaurants. On the larger ships, you also need to reserve some of the shows. This annoys some people, but we loved it. We much prefer making our own plans and it is incredibly easy to make reservations online before your cruise even begins.
At some point, someone will come on here and offer up a "nickel and dime" comment, but we did not experience that - at all. Yes there are a few things they charge for that Disney doesn't (soda, room service are all that springs to mind right now - though room service is free in the Haven). By sailing in a suite, we received free specialty dining, free alcohol, free internet, $300 OBC, and even a small credit if we had booked shore excursions through NCL (we didn't). All of those things cost extra on Disney. You do have to pay the gratuities for the alcohol and specialty dining package. This annoys a lot of people. It doesn't bother me one bit, as we would tip the servers anyway. Now it's just built into the cruise fare. Works for me! On our upcoming cruise we are starting out with $550 in OBC due to NCL's booking perks and TA perks. Honestly, I have no clue what we will even spend it on. We don't gamble, so we can't even use it on that. Oh well. We will think of something! We may end up using it to tip our butler and concierge

.
Our son was 19 on the one NCL cruise we have taken, so I can't speak to the kid's clubs. He loved it though! There were quite a few kids on board (summer in Alaska) and they all seemed to be having a good time. But I can't really help you other than that, sorry.
On the negative side, they do have a casino and yes, you will occasionally have to walk through or near it and you might smell smoke. If you are very sensitive about that, it could be an issue. My husband is allergic to cigarette smoke and my son has asthma. It still was not a big deal to us, but you will hear from others that it was. Everyone's different and has a right to their opinion about their own experience. It just wan't an issue for us, though. Also as a negative, on Disney we really enjoyed the enrichment programs - lectures and such. NCL really didn't do anything like that other than bring on a park ranger when we were in Glacier Bay to narrate. As we were out on our balcony, we couldn't even hear her. Oh well. They could really improve in that aspect!
In addition to our upcoming cruise, we are sailing with them in 2019 on a 14 night cruise to Italy, Greece, Croatia and Montenegro. They really do have some fabulous itineraries, as do many other lines (Celebrity, Princess and HAL all seem to offer some great ports). There is lot to choose from. Before you make a final decision, I'd recommend going over to Cruise Critic and checking out some of the forums for other cruise lines as well.
We also sailed Disney to Iceland / Norway and it was a fabulous cruise. But that was the very first one and the price since then has risen to an amount I'm just not willing to pay anymore. But everyone spends their money differently. For us, at this point in our lives, Penn State gets the biggest cut

. Also, being able to sail in a suite is perfect for 3 adults traveling together due to the extra space and privacy a suite gives you. (Though our son won't be on the next two - Penn State calls

) Sailing in a suite on Disney was never an option for us - we just could never stomach that price as we like to take several vacations a year. A suite on Disney would mean that was the only trip we took, and that just didn't work for us. To each their own, though. It's good to have choices.