Having read some of the negative reviews here on Tripadvisor and reflecting on my own stay, I have to wonder if they stayed at another, similarly named, hotel. The short summary of my stay in one of the superior rooms is that this is a fantastic hotel with wonderful service and better food, even if you are a vegetarian.
The superior room was of a reasonable size with the usual amenities (tv, fridge, a/c, fan, safe, etc.) and a rather usual hotel bed. Nice, clean and modern. Reassuringly predictable, if you will. The bathroom was a step up into luxury though: large enough to contain a bathtub, a separate shower and a separately enclosed toilet with a bidet. The tub was perhaps slightly on the small side, at least if you were contemplating joining your beloved in it.
Outside, you have a little terrace with a sympathetic lounger as well as some other furniture. Typically, you will have a view of the hotel grounds from here, which is mostly a lawn with a few trees and some sculptures, as well as the restaurant with bar and the pool. There is wi-fi but, being the Seychelles, don't expect groundbreaking speeds.
One nitpick: mosquitoes. The staff said almost no one had any problems with them but we were certainly bitten dry at any time of the day when we relaxed on our terrace and to some extent in our sleep. We could have wished for mosquito nets.
The food at Le Duc is stellar. Every other day there is an á la carte menu and every other there is a buffé. The buffés are good but it is the set dinners that really shine. What will be available for dinner is set and printed before breakfast, which means you have the whole day to decide where to go in the evening. As vegetarians, we found that the menus rarely offered a viable main course but the friendly and competent staff solved this little problem with visible pleasure and jokingly offered to name the unofficial vegetarian alternative after us. Not only was this alternative sensational every time but also completely different every time.
While it costs more, there is also another restaurant connected to the hotel, just across the street, right next to the beach: Le Café des Arts. Since we were so happy about the food at Le Dauphin, we only went there once. You could say that Le Café des Arts has the ambition to earn a star in Guide Rouge because all the hallmarks are certainly there with impeccable service, lavish surroundings and extraordinary food. Le Dauphin is fantastic but Le Café will not be beaten. Which means that Le Duc has no less than two fantastic restaurants!
Breakfast is what you would expect from a four star hotel. In other words, very good but not quite as lavish as you'd expect from a five star hotel.
The service was very good indeed. All the staff we came into contact with perfectly managed the line between friendly and familiar, bringing just that much personal touch to make you feel adequately special.
We've read that the hotel is not exactly on the beach but quite close. If 20 meters is not on the beach but quite close, than yes this is true. Le Café des Arts is actually blocking the view of the sea, but that is the only building between the hotel and Anse Volbert. The beach lacks the dramatic boulders of some of the more iconic beaches in the Seychelles but it offers a very nice view of Curieuse, St. Pierre and Chauve Souris. It is also a very spacious beach where you are supplied with hotel sun chairs and shade. The swimming is very nice with sandy floor and ample depth but it is heartbreaking to witness the enormous coral reef some fifty meters out, almost all dead. There are some few groups of juveniles making a living among what corals survive but mostly the reef is bleached and overgrown with seaweed. This same seaweed has a habit of floating ashore on the beach but we never let that concern us.
If you are two strong swimmers with fins, you could definitely swim out to St. Pierre, a small islet that offers very good snorkelling. Haven't checked but I think it is roughly a kilometre out. There's some boat traffic in the area so make sure you are visible.
In conclusion, we were very happy with our stay at Le Duc de Praslin. There are other four star hotels and quite a few five star hotels, but the location, the service and the food really set this hotel apart. We are coming back as soon as we can!