Before sailing on Carnival this past April, my daughter and I sailed on Royal Caribbean Navigator of the Seas and Oasis of the Seas. Loved both ships and had a wonderful time.
For the positive on Carnival Dream: My 17 years old daughter loved going during spring break and meeting so many kids her own age. The last two cruises we went in November and not many kids on board. I thought the people I met on board were a little more friendly compared to Royal Caribbean.
Negative: Since I only have Royal Caribbean to compare too, I have to say that Carnival Dream was very average comparing to Royal Caribbean. It just didn't have that "wow" factor walking on the ship like on Royal Caribbean. The serenity adult only section just didn't have the same feel as Royal. Very hard to find a chair because they are saved all day. The worst was the chair hogs! I thought it was so rude to save chairs all day without anyone sitting on them.
On Royal Caribbean the dinning room food and service were awesome! We felt every night we were eating in a high class dinning restaurant. On the dream the food was very average. The servers were very friendly, but felt they had too many other tables and didn't have the quality of service.
The shows were very average.