My wife and I had been on 2 cruises before, in Bali in 1998 and up the east coast of Australia in 2003. We had enjoyed them so much that when it was our 40th wedding anniversary we decided on another cruise.
Carnival Spirit was everything (almost) that we had hoped for -- large, wide variety of bars and lounges, very good food and lovely staff / crew. All in all, we had a great time and would do it again, in fact, probably will.
A few pluses and minuses: for me, physical fitness is a must, and I have used a Concept 2 Indoor Rower to train on for the last 15 years, since marathon running destroyed my knees and can no longer run. I was extremely disappointed to see Carnival Spirit had no rower in their otherwise very well appointed gym. My 2 other cruise ships both had plenty of rowers. Secondly, we were disappointed with the lack of late night activities for genuine night-owls -- only the nightclub, with its awful techno-dance rubbish music and the 24 hour pizza seemed to be open. The wonderful Club Cool with the superb rock band "Music Manila", closed at 12:30am leaving us nowhere to go, and we did not want to go to bed!!! I would seriously suggest a jazz / wine bar to stay open until say 3am. Other passengers agreed with us on this point.
The last moan: I was horrified at the danger posed by the low wrought-iron barriers surrounding the "Atrium". This goes up to 9 stories high, and yet a 5 year old child could easily climb these barriers (loads of hand and foot-holds),and fall to their certain death. A tragedy waiting to happen, I thought. I definitely would NOT take a child under 8 on this ship, because I would be freaked out all the time watching them anywhere near that atrium
And the good points? Dozens! Heaps of good food, just loved every food place on board. Wonderful staff and crew. Music Manila (geeze, the lead guitarist was as good as Hendrix or Clapton). Didn't try Green Thunder as we were always too busy elsewhere, but it looked damned exciting. Great entertainment, especially the juggler from Kiwiland, he cracked us up with his act. Also the mind-reader was brilliant. We were also amazed at the efficiency of embarkation/disembarkation -- smooth and hassle-free. Would we recommend it? In a flash, with the proviso above. There were all ages on our cruise, from pre-teens to elderly, and all got on very well and all appeared to be enjoying themselves greatly, as we did.
Ports weren't that great, not exactly Rome or Athens, but we knew that before we left so no problems. The beaches on Mystery Island and Wala were very nice, and the native people beautiful (and ingenious!). Port Vila and Santo mostly sucked, but that was only our opinion, others enjoyed them.