The location of the apartment is really fantastic. If you want to explore Vienna, you can visit a lot of places within walking distance. There are also great restaurants nearby. For 4 people, the size is absolutely fine, for 6 people in total maybe a little too small, e.g. bathroom (altogether the apartment is a bit smaller than it appears on the pictures). Depends in which room you stay, the apartment is relatively noisy, but if you know old buildings with courtyards, this is not surprising. The checkin/checkout was easy, the staff very nice.