The apartment is well maintained and large. It was sparkling clean. The check-in process is easy and clear. The only downside - there aren't any toiletries, so bring your own.
Location - direct metro line to the city center, around 15 minutes from the apartment door to Stephansplatz.
The staff at CheckVienna were very helpful, they offered to hold our luggage until the end of they day, as we had a late night flight and didn't want to carry our bags around the city.