My mom and I did this excursion just last week. It was very relaxing! They take you over on a bus, giving you lots of facts and a history lesson about the island. It's about a 20-30 minute ride over there, and yes, there is mostly poverty on your ride over there. Once you can see the water however, you won't think a bit about the poverty, only about how beautiful and breathtaking the view is. The day we went over there, the wind was so strong that the waves were just enormous.
DCL warned us about the undertoe, and even offered a refund if we decided not to do it due to the strong under-current of the waves. My mom and I didn't plan on swimming much, so we went ahead with it. We got to the beach, and they greeted us with a complimentary fruit punch (which tasted very peachy...you could get rum added to it if you wanted). There are plenty of comfy beach chairs to choose from...we walked a ways to a spot with an umbrella. Of course, you have to pay $3 if you'd like to keep the umbrella. You WILL get bombarded with lots of local merchants trying to sell you things...there's just no avoiding it...espeically hair-braiders. I got my hair braided there (because I wanted to...and because I wanted them to quit asking me). If you're not interested, a "No Thanks" will get them to leave you alone. What worked for me was wearing a visor and my headphones...they didn't bother me at all as I couldn't hear them. =) You also have lunch included with this excursion...they only have ribs, chicken, and fish I believe...I'm a vegetarian, so I just nibbled on the french fries and salad that also comes with it. After lunch, we had about an hour and a half more (about 2 1/2 hrs beach time total), so we relaxed on the beach, trying not to look at the naked people. We counted 13 people fully or partially nude. If this bothers you, I would suggest picking a different excursion/beach. It was kind of disgusting, but we lived through it. =) On the bus ride back, you can choose to either get off the bus at Phillipsburg to do some shopping or go back to the ship. We decided to check out the shops...although, we didn't find anything...so we ended up walking back to the ship, which isn't exactly a short trip. I suggest that unless there's something you really want to buy there, just ride the bus all the way back to the ship.
Overall, this excursion is very relaxing (with a few naked people here and there) and beautiful.=) Hope this helps!