We LOVED the Sun. We went last summer to Alaska, so I don't know about her Caribbean route, but we thoroughly enjoyed the ship. Our balcony cabin was roomy enough for the 4 of us, we thought the food was wonderful, the members of the crew were extremely friendly and always gave us good service, and the ship itself it beautiful.
I am planning on going on the Sun again one day -- right now, it's back to the Sea before she leaves the NCL fleet. While we had a great first cruise on the Sea, and are excited to go again, the Sun is a much better ship.