The apartment/studio is located at the edge of the hip Pijp neighborhood, one block away from the Albert Cuyp market (open almost all week), a short walk (<10 minutes) from Heineken Experience and 10 minutes more from the main museums -- Rijksmuseum, Van Gogh, Stedelijk and MoCo. Vondelpark should be only a litter farther away but we got there from somewhere else.
Not quite in the city center (walking distance of about 30 minutes, we did that several times), but very easily accessible via tram from central station and other places (we had no problem finding it on the first day).
Communication was simple and responsive. There is no special place to leave the luggage if you come early or leave late, but they kindly let us check in early (10AM!) on the first day (as the apartment was vacant in the morning), however in the last day they had guests coming so we had to store our luggage elsewhere. The owner also left some recommendations for nearby places, we checked the bagels place which was very nice and the hamburgers (The Butcher) which were great, so we're optimistic about the rest too :)
Downside seems to be maintenance: the apartment was not very clean (there was some construction work outside in the next door, so the entrance and the apartment floor had some dirt), the lights are a bit dim (with only some of the lightbulbs working), and there is only one (fairly small) closet which already stores the small fridge and extra blankets. There is also the bed which is really two bed put together (which is mentioned a number of times in other reviews), but to be fair, we only started really feeling it after our 6th (and last) night, so it didn't seem to be a huge deal.
All in all, it's a nice apartment in a nice location for a reasonable price (bearing in mind that Amsterdam is not a cheap city), and personally we had a great week in Amsterdam residing in this apartment.