I realize people on this site are probably seasoned cruisers but I will write this as a rookie because that's what I am. I just got off my second cruise. My first was with Carnival Fascination and my second was with Carnival Fantasy.
Both ships are ok. I don't think I'll ever travel with Fantasy again. It isn't anything big, it's a lot of little things that add up.
Fantasy is older and it shows. The staff are just a little bit less friendly and helpful. It's shopping (jewelry, clothes) didn't appeal to me as much as Fascination. The ships entertainment was not comparable. The show, trivia, etc. is higher quality and more fun on the Fascination.
Embarking on the Fantasy was slow and laborious, yet on the Fascination was quick and easy. Debarkation was just the opposite. The Fantasy was announcementless yet quick and seamless. You get the directions on TV and in several handouts. It just went bing-bang-boom. The Fascination was horrible. We were stuck sitting in the stairwell for close to 2 hours waiting for things to happen.
The food on both ships was similar, but again, like I mentioned before the Fascination is just a tiny bit more polished.
Empress level is a good choice for me for most of the time. It is near most things happening on the ship yet not near enough to be noisy. It is one level down from our restaurant. It is definitely NOT the place to be in rough seas. I think the next time I cruise I will get a balcony. I really miss fresh air. I realize most seasoned cruisers spend very little time in their cabins, but I spend a fair amount of time there as I am a "homebody". Being alone in my own room is comforting to me. I want to be able to walk out of my room and be near the ocean. BTW - I sleep with my shades/curtains open in my bedroom at home because I don't like being closed in. I keep the curtains on the ocean view window open too.
I went on the Fantasy for a New Year's Cruise - 5 days to the Bahamas leaving from Charleston.