We did not have poor service, we just didn't have any service after we checked in and were directed to our cabana. We were not concierge and I definitely wondered if that made a difference; as others have mentioned there is probably "pressure" to keep those guest happier. With that being said we still enjoyed the cabana and will always try to get one, even if the "dedicated service" they advertise is missing. On the other side of things I can definitely see where people would be upset because based on the description from the website:
During your visit to Disney's Castaway Cay, bask in the luxury and privacy of a deluxe beach retreat along Family Beach. Each well-appointed cabana is furnished with comfortable seating, a beverage refrigerator, safe, ceiling fan, plush towels and sunscreen. Outside on the patio, luxurious chaise lounge chairs, a freshwater shower, hammock and sailcloth shade are yours to enjoy amid spectacular offshore views. Fresh fruit and snacks are included along with complimentary bottled water and soft drinks. Dedicated beverage service is provided and alcoholic beverage packages are available for purchase onboard at an additional cost. Additionally, each cabana includes use of snorkeling equipment, floats, sand toys, and one hour of bike rental.