I stayed just one night at Gerd's apartment. The location is very central, just three minutes walk from the Central station, which was my main reason for choosing the place, because I was going on a bus excursion from the station early next morning. This worked perfectly.
Communication with Gerd prior to my stay was effortless and easy. He met me at arrival and showed me what I needed to know.
The room is nice, the bed is futon style on the floor but quite comfortable. There is a roof window right over the bed with no curtains (at least I didn't find out how it worked) so it will get light in-your-face if you want to sleep after sunrise. (Just bring a sleeping mask = problem solved.)
The bathroom is next door to the guestroom; large and clean with a bathtub, and nice towels and shampoo was provided.
Gerd and Ulli has a rather big dog, but she was friendly and quiet, so no issue.
The neighbourhood is central, but also a bit 'scruffy' - it's like the red-light district of Munich, with lots of stripclubs and sex shops. I don't mind, it's just colorful and exotic - but maybe Gerd should inform about this on his profile.
All in all I can recommend staying at Gerd and Ulli's for openminded people looking for a central place in Munich, with good service given by nice hosts.