In a nutshell: nice for one night if you are a castle lover or want a different hotel setting, but eat in the city and do not expect 5-star service.
At almost 200 euros per night (superior room, accommodation only), this is not a bargain hotel, but it makes for a nice one-night stay if you are looking for a charming, different hotel. There are none of the amenities (spa, fitness center, pool) you would expect at that price in such a location (small town 45 minutes away from Madrid) but the reason you're paying is for the building itself, which is a huge,12th century castle that was almost completely destroyed and has been fully and tastefull restored.
The hotel is only a short walk from the center of the town of Siguenza, which can be visited in a day. I would therefore recommend just staying at the castle for one night. Based on recommendations on local websites, we booked the superior room with a jacuzzi, but I would not recommend it: it had not been used for some time and was very dirty. For the same price, you can get a room with a terrace, which must be much nicer. The rooms are otherwise clean (slight piping problem smell in the bathroom) and quite big and spacious (double bed, reading area next to the window and sofa + one-seater).
The hotel's inner court and the bar are always full of tourists, so keep that in mind... but the rest of the hotel is for guests only and is worth exploring. Don't miss the tiny chapel, which you can see from the 2nd (floor).
The food and drinks at the hotel are of course overpriced (main tourist spot in Siguenza) but are still reasonable compared to the prices in a big city. I know many people complained about rude service, but our experience was ok, although not to the standards of a hotel of this price and category.
However, if you are looking for a good and cheap place to eat, go to the Bar El Atrio, which is right next to the cathedral. It is very casual and the clientele is mostly local. It looks like a bar and not a restaurant, but you can eat lunch and dinner there and have a good glass of wine for less than 2 euros.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.