This was one of my best experiences through Airbnb.
Firstly, the host couple were very welcoming, helpful and available when I had any questions.
The Airstream itself turned out to be such a wonderful experience. If you have never stayed in one before: think of it like a compact 4.5 star hotel room, but with a fully functional kitchen (stove/oven/microwave/fridge) and a dining space.
WiFi was good and due to the functional design there is easily enough table space for two people to sit comfortably and work on laptops.
The shower space is a little compact, but even at 6 ft 2, I could happily shower standing up and there was also a built in seating space within the shower.
There is a good quality air conditioning system and I believe a gas heater (which I did not need). I stayed during the very middle of the Texas summer heat and the air-conditioning kept things manageable during the day time but importantly could go very cold at night.
The location of the Airstream on the site is secure within in the fenced compound but also has a good level of privacy as it is away from the main building on the property.
In summary, I would say it was great a option for one person to stay for a few months, but a couple could also easily enjoy this for at least a few weeks.
As you can see I really enjoyed my stay (approximately a month) and plan to stay there again some time in the future. I hope this review helps others find this wonderful option in Austin.