The room was great. There was plenty of light, and the bed was comfortable. Many complementary objects were provided. The location is excellent, with only a 30-minute walk to the center or a 5-minute walk from public transport. The breakfast was delicious and abundant, with plenty of sweets and salty food.
Nonetheless, aside from the room, it is not a 4-star hotel in several aspects. For example, there are no other facilities other than the breakfast room. Some things for breakfast are old or reused from previous days (like the cocktail bread or the wheat biscuits). The room was not vacuumed, as the same piece of string stayed on the floor the entire time (8 nights); but the rest was clean.
Overall, I would say it is an excellent 3-star hotel and an okayish 4-star. If you stay only in the room and use the hotel facilities only for breakfast, you will love it. If you expect anything more than that, you will probably be disappointed.