Absolutely the best - I keep raving about it myself! I rode the public systems in many cities, but Vienna is ahead of them all in every aspect!
Like, try Paris, for example - and imagine you are in a wheelchair or have special needs! Hardly a elevator or escalator to be found, and going from the Metro onto a bus, you have to pay again! Not so in Vienna. Your ticket is good on any public transport, and also the S-Bahn and trains of the ÖBB within the city Zone 1. Want to go to the airport? Fast and efficient, and at less than half the price of the highly advertised CAT airport train (just buy 2 regular tickets to get to the airport, since it is outside Zone 1). And here is some additional advice to visitors going to the airport: go with the regular ÖBB train, because you also use the same ticket (plus one additional) to go from anywhere you are in the city. Don't think the CAT train gets you there faster: it runs between the ÖBB schedules on the same track! I live in Floridsdorf, and I am at the airport within a half hour.
@mammasitta - We have something in common: since I moved back here, I do no own a car (I had, out of necessity, 3 vehicles when I lived in Canada). There is no need for it in this city. My sis sometimes offered to drive me home, and I used to decline, because its an easy choice between sitting in traffic jams for over an hour, or getting home in comfort within half hour even from the furthest place.
And the absolute hammer for residents is the Yearly Pass! For the price of a few parking tickets, you can travel all year long as much as you want.
It costs € 365,-, so one € a day! Being a Senior, I pay even less.
Check it all out at WIENER LINIEN the site is in German, but there is a (somewhat different in content) tab for English, top right navigation. I also want to add that the Schedule Info is now also available on Google Maps: just enter your starting and arrival point addresses on the map under Directions, and click the icon for public transport.