The apartment is only a 7 minute walk from the train station Altstetten and the connections to the main train station and airport are really good and also not too far away.
Between the train station and the apartment are 1 Migros, 1 Coop and 1 Migrolino (Gas station - open 24/7) with good prices (for Zurich) and all the selection one needs for their stay.
In the other direction there are an ALDI and the LetziPark shopping Mall with more selection and more food choices.
Right downstairs in the neighbouring building is a really nice cafe with a decent selection of drinks and food or one can go for a quick grab at one of the places near the Altstetten train station.
Mars always replied within hours to any of our questions and was always available when we needed anything!
The apartment itself is kept simple (which we prefer) with a very large bed for 2, a beamer with TV hookup underneath the bed, decent WiFi, beautiful shower, washing machiene, dryer, and best of all, a capsule coffee machiene.

So all in all this was one of the best apartment stays on Airbnb (location and host) that we ever had and we are so definitely looking forward on staying there again.