Stayed here for a week in August. It is a nice hotel, and it is ideally located right next to the beach in Las Americas. The staff is friendly and generally helpful.
Having said that, this is not a "real" five star hotel. The restaurant is ok-ish, but that's about it. Breakfast was not bad, but we had dinner there once and this was rather disappointing. I'd say its a 4*+ at best overall - nice rooms, friendly staff, but nothing that would make it stand out. Also, this forms part of the mare Nostrum resort, which consists of the Sir Anthony and two other adjacent hotels (marketed as 4*), both being much bigger than the Sir Anthony. This means that most of the facilities are actually in those other hotels a short walk away - certainly not a catastrophe, but not ideal either.
Finally, there are parties at the other two hotels which can make the place noisier than necessary on some nights.
Overall, given the price, I'd say there are better choices on the island - either save some money and go 4* or get the real deal for the same money (or maybe a bit more).. read more