We (family 2+2) have stayed in Heidi's place for three days and here is our review:
Communication with host - very efficient, quick responding.
Location - quite central but within walking (15-20) minutes from the train station/city centre. Otherwise there is tram stop right at the building. Keep in mind prices for public transport in Oslo are rather steep so walking is a cheaper option.
Apartment is on the 3rd floor (4th level) so there are couple of flights of stairs up which we did not mind at all.
Parking - very challenging. There is NO parking on the premises, no private parking. If you travel by car you have to park at the curb along the local streets. Finding available place is very difficult regardless of time (day or night). Normally you have to wait till somebody leaves and than be lucky enough to get into his/her place.
Cleaning. Heidi does not charge cleaning fee and expect guest to clean. This is however nowhere described in the listing and looking up for it in the reviews is not something prospective guest should need to do. In addition there are different "cleaning standards" and different "cleanliness expectations" so you might be lucky and have clean apartment when you arrive or it can be quite otherwise. Apartment is richly decorated and we bit complained about amount of dust (some of family members have allergies to dust)
Summarizing - okay stay.