So-- I enjoyed the ship-- didn't enjoy it as much as a
Disney cruise and in the future would spend the extra on Disney (maybe unless we had the chance to try out one of the RCL mega ships that has a ton of activities that
DCL ships don't have).
Basically, the ship is very nice-- it didn't feel like a step down from DCL in terms of quality of the ship itself. I did think the food was probably one step down and the service was probably two steps down. No particular problems at all-- just not the same feel of the staff really going overboard to please. There were certain exceptions, of course. In terms of food and service, the specialty restaurants were fantastic. Our meal at Chops was probably the best meal I've ever had on a cruise ship.
There is definitely a heightened feeling of trying to get you to spend money on the RCL cruise ship. That is certainly not absent on DCL, but I thought it was significantly more pronounced on RCL. I don't think the net result is to make RCL as expensive as DCL, but since it is in your face a bit more, it was bothersome. I would honestly rather pay a bit more up front and not have to make as many monetary decisions while on my trip.
That said, we spent very little on the ship. Largely because of the absence of Disney merchandise.
The kids club space is certainly much less impressive on RCL, though the programming is more structured-- I can't say this is better or worse, and our daughter had a fantastic time in the kids' clubs on both cruise lines. (She is 3-- she's been on DCL 3 times but only old enough for the club once. DH and I have been on DCL about 8 times).
I wouldn't say I was disappointed and we did have a very nice Christmas cruise. It's just not Disney, and we are huge Disney fans. I wouldn't hesitate to go on Brilliance or RCL generally. You just have to know ahead of time that you are getting a different product that may be missing some of the elements that make DCL special for you. It's still a very nice product. It's just not a product I personally would choose to buy over a DCL cruise, in most circumstances.