Lovely hotel very close to the Centraal station and the old city centre. Staff were always friendly, helpful and welcoming. We did have cause to complain about the noise from the room above on our first night until the early hours, and not only did reception move us to a different room, but also said they would speak to the guests involved to avoid a repeat with subsequent guests. So, very well handled all round.
Breakfast is continental style and served in the multi function reception/bar/ breakfast area. In reality it is much better than that sounds, and actually a very relaxing atmosphere. The breakfast itself was very fresh, and unlimited, including tea & coffee.
There were a couple of minor negative points I found with this hotel. Firstly, as there are no tea & coffee facilities in the rooms this could be provided free to guests in the reception area. Coffee is only €2, but still, I think it would be a nice touch. Secondly, the bathrooms are beginning to look tired. There are some signs of a refit, but since these are exposed screw holes and cut tiles it overshadows whatever new bits have been added. Really not a big problem, and I'm being fussy for the sake of an honest review, but it's these things that make it four instead of five stars.
All said though, for proximity to the station and the centre, along with comfort, price, and friendly staff I wouldn't think twice about returning to, or recommending this hotel. In fact two years ago I reviewed hotel JL no.76 in amsterdam. It was dearer than Sint Nicolaas but perhaps a little better at pulling off a boutique hotel style. It was also further away from the centre, and the station. Taking everything into account, of the two, I'd probably choose the Sint Nicolaas.