I stayed in the backroom for 3 nights with two friends (total 3 people): everything was perfect from the check-in to the check-out. The room is perfect for two people, but can comfortably suit three, as guests are provided with a double bed and an extra (self-)inflatable mattress, which is as comfortable as a bed. The room is heated by two radiators, and if this isn't enough for you, Shawna the host will provide you with warm blankets. The toilet is a bit tiny and only includes the bowl and a shower; however, there is a sink with a mirror in the room.
A small hotplate, pots and pans are available for cooking, there is a fridge in the room as well as a kettle and a microwave, so everything you may need for a short stay is there. Not to forget the hi-fi system with tuner cd and aux-in (cable provided)!
An AlbertHeijn supermarket is almost next door to the place (about 30secs walking, amazing!) and you will find several restaurants, a cheese shop, coffee shops, cafés, pubs, and so on... on the same street.
As for the location, again, just perfect. Located in the Jordaan area, the backroom is at a short walking distance (10-15 mins) from Dam and Leidsplein. We never used public transport, simply walked, as the location is very handy (though renting a bike would be the best solution).
Our host Shawna was extremely helpful and lovable. Will I ever go to Amsterdam again, the backroom is the place where I'm going to stay.