Lars and Frederik's place is super nice, and we loved having the space to ourselves. They were also really accommodating for our late flight out (after check out).
The apartment sets you up well to see the little mermaid statue and some parks, but is a good walk from the train station, Tivoli gardens, and the more central areas of town. That said, Copenhagen is very small and easily walkable when you get the hang of the twisty streets.
Check in was a little rough for us, as we didn't have cell phone service or wifi and were unsure of where exactly the apartment was. We couldn't find Lars and when we got wifi, he wasn't super quickly responsive. That said, it all worked out great.