I stayed in a single room (with balcony) for 3 nights while on business in Amsterdam. Everything was spotless; there was good linen on the bed (2 single beds in my room) and good towels in the very tiny bathroom. I am used to the high price to quality ratio in hotels in Europe's major cities so was not surprised by the rather cramped quarters but felt I could have done better. The door to the room, for example, bumped the table when opened so couldn't open fully and the door to the bathroom was more like half a door, requiring me to turn sideways to get thru (and I'm thin). The stairs up to reception were, as others have mentioned, extremely steep and it felt like mountaineering to climb them. Friends staying in an apartment in Amsterdam had a similar situation so this is common in these old narrow buildings but I've noticed that some small hotels do have lifts.. The Nadia staff carry your luggage up & down but be aware that this hotel is not for everyone for these reasons.
Extremely friendly staff on the reception and, like almost everyone in Amsterdam, they spoke excellent English. There was a long wait before I could get into my room which was irritating as I had business to do. I was invited to sit in the tiny breakfast room while, presumably, someone made the room ready. Not sure about this - it was never explained. As this was mid afternoon, I felt this was a slip-up on the hotel's part.
Breakfast was fairly basic but included in the room rate so I can't really complain about that. You couldn't expect breakfast in this standard of hotel to be lavish.
I did not particularly like the area in which the hotel was situated but I'd be hard pressed to say which would be a better area (except perhaps further into the Jordaan area?) In my opinion Amsterdam is a scruffy city and the charm of the canals is tempered by the amount of litter, graffiti, and the general down-at-heel look of the place and the people (inhabitants and visitors!). Just my opinion after a year of quite extensive travelling in Europe... and I thought the same when I was last in Amsterdam about 20 years ago.
My husband and I are planning to return for a couple of days in October to catch up with friends from Australia who will be ending a Danube cruise there and I will be looking for another hotel. I don't want to be hard on the Nadia which is OK for its price bracket but I know that, with my husband in tow, we will need to move up a notch for him to be happy. We both like the old style of architecture and fairly small hotels so I am considering some of the other suggestions in trip advisor reviews such as Hotel Brouwer and Hotel Fita.