It's a great apartment in an unbeatable location. The place is small but well organised and designed and had all amenities you could wish for, even some snacks, oats and pasta. When we arrived we also found a bouquet of fresh tulips in the living room, which was a lovely touch and made us feel welcomed! It felt cosy and very much like home. The host sent us very detailed instructions of how to get to the apartment and responded very quickly when we had a problem with opening the door. He also provided a thorough plan on where to go and what to see in Oslo which was super nice of him and very helpful.
Only one downside I could think of is the noise of passing trains at night - a railway station is just next to the building, so if you are a light sleeper and like to keep the window open at night like us it might be a bit annoying. But you barely hear it when the window is closed. We got used to it and it didn't bother us personally.
We would definitely stay again whenever we are back!