I had a good stay at Niels place for the most part - the listing was as described, and a great value for the area. Having a private (and remodeled) bathroom was a bonus.
The issue I had, which was pretty unsettling, was when I came home one day to find a woman showing my room to a potential tenant. She looked very shocked/startled when she saw me, so I could tell she wasn't expecting me to be home and knew she shouldn't be in there. It bothered me that she felt it was ok to let herself and a stranger into my room while I wasn't there. I had money, my passport, and other personal items out on the desk. It left me feeling pretty unsettled the rest of the trip knowing that anyone could be going in and out of my room at any time, so I started hiding my belongings every day when I went out, just in case.
If you're looking for a clean place in SOMA that's a good value, this is definitely it, just use caution as you won't have any expectation of privacy or security in the room itself.