My wife and I stayed four nights at the Alchymyst in early April. Good points. The hotel is beautifully furnished; the location is excellent - short walk to the Charles bridge, castle, tram and bus stops. Room service was prompt and good qaulity food; and there are some good local restaurants nearby. (Try Gitanes or St Nicholas Pizza just down the hill). Pick up from and delivery to the airport with the hotel car were efficient and courteous. All the staff we met were anxious to please.
Some issues - if you're a light sleeper you might need to ask for a quiet room. We had trouble on the first night and were moved, on request, and without argument, to a quieter location. The spa is excellent, but the pool is really a plunge pool. Fine for kids or aquarobics, but not one in which you can swim laps. There were a few other details that weren't quite right - not big enough perhaps to spoil our stay, but enough to prevent us giving a top rating.More