We stayed with Mark over Christmas (2016) and his place is amazing. The bed is firm but comfortable, the shower is amazing and the room feels spacious. Privacy is good, though you can occasionally hear outside noises or Mark's family, it was never enough to disturb us. From the art, to the plentiful storage, to the amazing shower you can tell that much care was taken to create a pleasant and comfortable place for folks to stay.
Mark was in great communication with us from beginning to end and was even able to accommodate a slightly early check-in, though you should not expect such treatment because his ability to do so is based on whomever is staying with him previous to your arrival.
As for the location, I suppose it depends on your preferences. If there was any reason what-so-ever why I wouldn't stay with Mark again it would be because of the location. It's not too far out but it's not close either. Even for many destinations in Brooklyn it's an hour by bus and/or train. The neighborhood isn't unsafe, but there is quite a bit of trash in the streets and on the sidewalks.
All in all we had a great time in Mark's place and I wouldn't hesitate to stay with him again.
Did I mention how amazing the shower is?