My friend and I stayed in the room with 2 single beds and overall had a nice stay. Nima's flat is clean, and we appreciated amenities like tea, coffee, spices, etc, as well as use of the kitchen. As mentioned in the flat description, bring your own toiletries (soap/shampoo), although towels are provided. The room was a bit small for the two of us, especially with no lounge or community space except the kitchen (which does have a table and chairs).
But if you're looking for a clean and comfortable spot in Amsterdam that's more of a base than a place to hang, this works well. There are buses to Amsterdam Centraal station right outside the door, and the ferry is a 15 minute walk away and then a (free!) 12 minute ferry ride to Amsterdam Centraal. It's also a green, quiet neighbourhood, which is brilliant.