I stayed at Samuel's place for almost four months, from mid October until early in February, and definitely recommend it for long stays. The building's location is great, close to metro station and a lot of restaurants and grocery stores. I could find everything I needed in walking distance (strongly recommend this really beautiful Persian cafe, Cafe Aunja, 5 minutes walk from the building).
The place was very clean. Samuel is very helpful and responsive and will take care of any problem that you may have in the apartment immediately and will make sure that you have a pleasant stay. The building staff were also very helpful and responded very quickly to maintenance requests. Also, I saw a few roaches in the apartment after a couple of months that I had stayed there (none until then), the maintenance treated the apartment which was very effective and didn't see any after that.