After 20 cruises I chose this one to try the big new RCL ships. More importantly it included 2 ports of call I had not been (Labadee and Falmouth) and the price was low compared to other sailings I had seen. I mostly have cruised based on destinations and ports of call, to get an overview of places I may revisit for a longer stay and also when I get what looks like a best price.
I met my goals - the ship was interesting to check out with both advantages and disadvantages and the new ports were worth the visit. The other port this cruise visited, I know well from many visits both land and cruise - Cozumel - so I went scuba diving with a dive shop I use there and that was great too.
I would not chose to cruise again just to go on one of these large ships. I would book based on destination and price. Despite being a nice beautiful ship - the ship is not what I cruise for and Allure was that same in that respect - better but not enough to make a difference to me.