We stayed in Oslo for a couple of days and really liked the apartment! The location is great, everything you need (subway, bus station, supermarket, even a park) is in walking distance. You can also reach the city centre just by walking, although it takes a while.
Also, Nicolas is a very friendly host! He lives in the apartment next door and whenever we saw him he made sure we had everything we needed and gave us tips on where to go. I would recommend staying at his place!