Well there are more people, but there are still plenty of chairs and things at the beach for sitting on, and if you can work around prime lunch time, that is a benefit as well since you won't be waiting in line for food as long if at all. It's not like visiting Magic Kingdom on Christmas.
The Dream itself is bigger so the entertainment venues are larger as well. You'll see that the layout of the ships is different, the adult areas are at the aft end of the ship for example. But notable differenences are the adult pool area satellite falls, the addition of Remy- the adult French Restaurant to the normal Palo, and the glorious aquaduck water slide. You'll also see an upcharge snack location Vanellope's Sweet Treats. If you have kids check out the MidShip Detective Agency game. Can be started and stopped whenever you want, so it is good if you have a few minutes before dinner, or between trivia sessions.
Don't worry. It will be fine!