Booked a single room for a two-night weekend stay. The room is small but perfectly comfortable for a solo traveller, and there are plenty of clever little shelves and storage, plus everything you'd expect from a decent hotel (TV, Nespresso machine, even a complimentary bottle of water). I actually really liked it.
Bathroom was also small and perhaps just a little too much so, with not much space to dry after shower etc. But again it did the job; walk-in shower with curtain, hairdryer, couple of shelves and two hooks on the door.
Staff were very friendly on check-in and check-out. I didn't have breakfast so can't comment (only because I was meeting friends elsewhere for breakfast). Apparently they do bike hire too but again I didn't use it.
Location was about 20 mins walk from the centre, Centraal station etc, and a pleasant enough walk day and night.
I would definitely recommend the Lancaster and would stay there again.