Fantastic location! Positives: responsive host, flexibility with check-in (we arrived a little before check-in, but Paul met us at the property and got us checked in about an hour early), right next to Wien Westbahnhof, quick Wi-Fi, good water pressure, comfortable beds, and good local recommendations in the apartment.
The location was excellent! Westbahnhof had access to the airport bus, trams, and the subway all within a 5 minute walk. Also, it had a grocery store, great pastry place, various restaurants, a place to buy an Austrian SIM card, and lots, lots more. It reminded me of an American shopping mall, but with links to all the transportation you could need to get around Vienna.
Negatives...none! The only thing I'll point out is that 1 of the beds is loft-style, so with kids, we had to be quiet at night so they could fall asleep. Just pointing it out for future travelers with kids. Thanks for the great stay!