Great place to stay!
The flat is just as on the pictures. Well-equipped kitchen compared to most places, nice bathroom though larger people might find the shower a bit narrow.
Communication with Jeanette was supereasy. Check-in/out takes place by fetching the key from a safety deposit box at the local 24hrs kiosk.
The area is rather hip and the park around the corner is one of the nicest spots in Oslo, don't miss the view at the top of the hill.
The only drawback is that the flat is on the elevated ground floor with windows opening on a dark backyard (bakgård), and you need to draw the curtains for privacy. It wasn't a significant disadvantage for a few days' stay though.