We never heard of these before encountering one in Vienna in September. We walked by, noticed it looked inviting, and stopped in for lunch. It took a minute to understand the concept but once we did it was fast and efficient. They hand you a chip card when you walk in. You stand in the pizza, pasta, or salad line and when you get to the front they make it to order while you stand there (the pasta they use is fresh so only takes a minute). The cook hand it to you and you tap your card on a pert on the counter, which enters the item and the cost onto your card. You can add other things as you wish, or go find a place to sit. The seating is at longish shared tables in a bright, modern setting.
The two men ordered the pasta, and my sister and I had soup and salad. My husband liked his pasta carbonara so much he now altered his own recipe for this dish to make it the way they did.
It was all very nice, and inexpensive. When ready to leave, we each handed our card to the cashier and paid the amount indicated.
This one was inside the ring near St. Stephens and the main pedestrian street, but we subsequently noticed another closer to our apartment in the 3d District. It never occurred to me that it might be a chain until I noticed one in Basel. Turns out they are in over 100 countries on 5 continents ( but very few in the US or Canada). The original was started in Hamburg in 2002.
This page from their U.K. and website shows an accurate picture of the interior, and explains the concept and the history.
http://uk.vapiano.com/en/about-us/about-vapiano/
I doubt we would go for dinner, which we like in a more relaxed and quiet setting. But we would happily go for lunch. Which we just did, vicariously, as my husband made carbonara yet again.