My girlfriend and I stayed at John's place for two nights. The apartment is well located in the center of Oslo and it is a very good starting point to visit the city. The apartment is also very clean and well kept.
Upon our arrival, John welcomed us kindly and gave us a lot if suggestions on what to see and to do in Oslo.
He is a very nice and available host and he promptly replied to all our questions and needs. During our stay we had a couple of missteps which, thanks to the efficient communication with John, were easily overcomed.
Overall, we strongly recommend this accommodation!