Håkon's place is great. I travel to Oslo about once a year and this is the best of the many places I've stayed at. It's a small apartment, but it has everything one needs and it's in a great location, with easy access to shops, an excellent subway station, and Frogner Park. I greatly appreciated the fact that it's directly above a first-rate supermarket -- non-trivial in Oslo -- and that my newly favorite cafe is right around the corner.
Also: Håkon is great at communicating. Whenever I messaged him, he responded helpfully within a few minutes. That really adds value to one's stay.