My wife and I stayed in Domaine de l'Astragale end June begin August 2011. We chose the hotel because we wanted a quiet place to relax but still near enough to Saint Tropez allowing us to go shopping or having a drink at the harbour when we felt like it. This is exactly what the hotel offers. It is only a 15minute walk from the center/famous harbour of Saint Tropez. The hotel itself is an oasis of peace (lot's of space, nice trees and flowers and beautiful Mediterranean style buildings add to that summery feeling). The pools are nice (and hot, which is great for swimming some laps early in the morning before breakfast), but we preferred the private beach (Bouillabaisse, just across the street). The private beach is really a plus to this hotel; we didn't even go to the famous beaches at the other side of town (Pampelonne, Bora Bora, Nikki etc.).
Our room was very large (Chambre Azur avec balcon) and was just perfect: amazingly large bed, lots of space both in square metres as in height, bathroom with bath ánd shower (but only one sink; two sinks would've been better), separate toilet, flat screen (never used it), silent airco, mini bar, very fast WiFi connection etc. We took a room on the first floor with a balcony which was slightly more expensive because we thought the rooms at ground level would not give a lot of privacy, but looking back at it this was probably not necessary.
Semi board allows you to have lunch or dinner, at the hotel restaurant. The menu at the hotel is valued at EUR 53 for whichever 3 courses you chose from the menu (i.e. if you had to pay for 3 courses, you would pay substantially more than the EUR 53 arrangement). Semi board also allows you to spend EUR 53 in another restaurant of the group Alp'Azur (i.e. you chose whatever you like from the menu, if it's less or equal to EUR 53 you are not charged extra for food, if it's more than EUR 53 the surplus will be charged extra to your bill). The hotel restaurant is very good but maybe a bit too gastronomic to eat at every day during your holidays. Therefore we switched between the hotel restaurant and the Bouillabaisse restaurant at the beach. The Bouillabaisse is very well located on the beach (in a typical fisherman's house with a large terrace), is much more causal than the hotel restaurant and has a much larger menu. We really loved having lunch and dinner at the Bouillabaisse (and having strong french espresso's until late at night on the terrace). The wine list in both restaurants is nice and complete (not cheap though). Being in the VAR you might consider having some local Côte de Provence wines (I would probably not buy a Côte de Provence at home, but the ones we had were all very good), which will prevent your bill from increasing to much.
As already mentioned, except for the hotel restaurant and the Bouillabaisse which is basically the second hotel restaurant, you also have the option of having your semi board at the other Alp'Azur restaurants. Make sure you confirm (and re-confirm) your reservation with the reception at the hotel. We had the unpleasant surprise of not having a table in one of the other restaurants after having booked one at the reception of the hotel earlier (some kind of misunderstanding, which was never entirely explained). Together with having to wait for new towels for over 20 minutes one evening, this was the only bad point throughout our stay.
Breakfast is good but don't expect a complete English breakfast buffet (although you can order just about everything from an extra breakfast menu). Croissants are of course excellent!!!
The personnel is nice, polite and helpful (except for the misunderstanding with the reservation in the other restaurant perhaps).
There is a nice and new tennis court at the hotel, but we didn't use it.
You can park your car for free in a car port or in the shade of a tree. This is important for Saint Tropez where parking spots are rare and awfully expensive.
Concluding, this is an expensive hotel but it is worth it. The rooms and restaurants are excellent and the location is close enough to Saint Tropez to walk. The private beach and beach restaurant are really a plus to this hotel.