Catherine's place is great! It is not in the center of Copenhagen but you can get there quickly either by bus or train. While I was there it only took me around 5-7 min walking time to get to the train station (Dybbølsbro) and then about 5 more minutes by train to get to the center (Nørreport). You can also take the 7A bus ( it takes less than 5 min to walk to the bus station ) and go to the central station and from there on you can basically go anywhere.
The appartment was very nice and clean. It was a cozy place with a great view. We had a great time and liked the area as well. :)
Catherine as a host is wonderful and is always quick in response. Definitely recommended!