We just did the Destiny last April and had a blast. We had done 2 previous cruises with Carnival with no problems but were concerned as well due to some negative reviews. The crew, ports, food, and overall cleanliness of the ship was fabulous! I did notice the Destiny is showing 'some' signs of her age, that is to be expected but nothing to complain about. There were some people complaining about the Puerto Ricans but we're from Canada and love the diversity.
In San Juan we stayed at the Wyndham as well and it was perfect.
As for the ports, Aruba is AMAZING and my favorite port so far! We rented a jeep from a place right outside the ship for $80 for the day. You can't get lost in Aruba because which ever way the divi-divi trees are pointing is the way back to your ship.
Have a wonderful time!