My wife and I went on the Carnival Legend in January 2013 with another couple. We had not been on Carnival in a while, and were fearful of an experience that wouldn't live up to recent cruises on other lines. In summary, it was much better than expected.
Ship - Some people had written about this older ship not being in good shape. I didn't see it. I thought it was in excellent shape for its age (about 10 years old). The decor, while a little gaudy at times, was well done. Carpet, railings, stair wells, etc. were all well maintained.
Cabin - We had an Ocean Suite, which was very nice. It had a whirlpool tub, a separate dressing area, and plenty of closet space. The bedding materials were first rate and the bed was comfortable. Our steward Ryan did a nice job. The only negative was that the TV was difficult to operate.
Food - We don't have high expectations of cruise ship food anymore (except in the specialty dinng rooms). We were pleasantly surprised by the food in the main dining room. I would say it was the best I've had in quite some time (better than the last Princess, RCL, HAL cruises we went on). We did eat in the steakhouse one night and it was, of course, fantastic. The lido deck dining was good, but nothing super. The only thing to stay away from is the scrambled eggs at breakfast - get a fresh made omelet instead.
Entertainment - The two dancing/singing shows in the main show room were really good. Many of these types of shows use track music anymore. However, this had a full show band (which also played some sets in other venues around the ship). They also had a magic/dance show that was very good. The tricks were pretty high level for a cruise ship. The DJ was a little older and didnt play all the rap/hip hop as we have found on other ship discos. The other entertainment was pretty weak, but not unusual as compared to other ships.
Shore Ecursions - Cozumel - we took a ship to Passion Island. This was a nice day at the beach and I would recommend it. Rotan - we stayed at the beach by the cruise port. It also was a nice, relaxing day at the beach. Don't take the chair lift to the beach. It is expensive and doesn't save that much walking. Grand Cayman - we took an excursion to Stingray City for about the fourth time. This was on a catamaran, which I would highly recommend. The other ships that go out there back people in shoulder to shoulder, and it is very uncomfortable. Swimming with the stingrays is definately a "bucket list" experience that you don't want to miss. Costa Maya - we were supposed to stop here, but couldn't because of high seas preventing docking.
Other - even though this was our third time on Carnival, there was no "welcome back" reception for us like other cruise lines do. Disembarkation was fine, but didn't seem as smooth as some of our other cruises.