We thought the Royal Service upgrade was well worth it. The biggest benefit is not really advertised - the RS rooms are either on or very close to the beach, whereas the other rooms can be a significant walk or even a bus ride away. Aside from that, access to La Palapala (exclusive restaurant for RS) was another huge benefit, as it gave an option that didn't require reservations and had lunch options that weren't the standard buffet.
The beach itself is amazing. There are plenty of cabanas/chairs so that you can easily find a spot either in the sun or the shade.
The biggest asset that differentiates this hotel from offers is the staff:
Rafael, our butler, was amazing and made sure we didn't want for anything. His English is also exceptional, so we never worried about a communication gap.
At the RS pool bar, Jose Louis, Jensy Ramos and Maximo were always extremely friendly, remembered our names and our orders, and went out of their way to make sure we were happy.
At the North Ave bar, we became good friends with Leandro, Julio, Jesica, Juan & Juana. Aside from being great bartenders, they gave us great tips about the DR and the resort.
We booked flights, transportation, excursions, and the hotel all through Expedia. This was our only real complaint about the trip, and we would recommend using another site. Expedia was very disorganized, and we wasted a significant amount of time on the trip sorting out their mistakes or attempting to make contact with their reps.