I stayed here four nights and had literally zero issues. The timing worked out well enough that David picked up me from the airport (on his offer; it's obviously not something I would have expected or would expect an airbnb host to do, but it happened to work out in this case) - this made finding the place and coordinating the check-in a non-issue. The space is very nice - it's small, but perfectly adequate for one person, and still would be just fine for two. The room is on the fifth floor - this wasn't a problem for me, but just fyi for anyone reading this that the building doesn't have a lift.
While you can occasionally hear some noise from the streets below, it was never a problem and certainly no louder than anywhere else (it's a fairly calm area, anyway). Generally, especially at night, it was very quiet. The skylights have electric shutters, which means the room can be made very dark even if it's bright out. With the shutters open, the room has plenty of light.
The building itself was undergoing some electrical work during my stay, but this didn't cause any problems for me. While the building's interior (i.e., the common staircase) is quite old and could probably use a bit of work, David's place was incredibly clean and modern. The wifi worked very well, and David has provided a couple of 3-outlet power strips (FR plugs; one on the wall, one with a short cord), which made charging phones/etc infinitely easier than hunting around for additional outlets.
The apartment is situated next to the river - this made getting around quite easy, as it's really close to the city center. There's a nearby tram stop, as well. Even at night, there were plenty of people walking around, so I never felt unsafe.
David was responsive and communicative through the entire process. I have no problem recommending his place to future airbnb-ers.