There's good news and bad news about Marcel's place. The good outweighs the bad, so we'll get the bad out of the way first. Marcel blamed me for leaving the terrace roof door open during a rainstorm and getting the interior of the building wet. He sent me an angry message rather than talking to me in person to find out what happened. The truth is, the person who greeted us, Robert, did not tell us it was our responsibility to ensure the roof terrace door was closed and we never went onto the roof after our initial tour with Robert. Unfortunately, this soured my (and my wife's) experience of the place.
Also, expect that the "complimentary Dutch breakfast" means make your own breakfast. There were some breads and toppings out for us and we apparently were expected to help ourselves to eggs and other items in the kitchen, but again, this was not made clear.
The only other minor thing is that the water in the shower drained very slowly and sometimes overflowed a bit onto the floor. We put a towel up against the shower pan to manage this.
Otherwise, Marcel's place is in a terrific location. Just across the street from the Anne Frank House and within walking distance of many attractions. I think the price is very good for the nice room and accommodations. I never met Marcel in person, but Robert was very kind and helped us with our bags up the (very steep) stairs even though he seemed to be having a problem with his foot or ankle, poor guy.
It was no problem sharing the water closet with the other couple on the floor. I think, in hindsight, we would have preferred their room which didn't have the shower/sink inside of it, but the detached bathroom they had in the hallway was much bigger than the small one inside our room.
While I wouldn't go back to Marcel's because of the communication debacle, I think many people would enjoy the location and accommodations he provides.