It is a scenic road, but also rather full. From the highroads in Austria I prefer the Silvretta, and the Gerlospass over the Glockner Hochalpestrasse, but that is personal. If you need to from Zell am See to Linz it is however the most logical road to take. You can also so take the Gerlospass, if you go from Innsbruck to Zell am See. You then enter the Zillertal at Jenbach, from there follow the signs Gerlos, and after that Krimml, from there you can head to Mittersill and to Zell am See. This should be done by car, and is at least a lot less touristic, and although the pass itself is lower, it has some beautiful views towards the Grossvenedigergruppe, and the waterfall near Krimml. This by the way is hiking paradise, if you can spare a day, take a walk to one of the cabins in the Habachtal or the Hollersbachtal. (between Krimml and Mittersill.
If you have no experience with driving in the mountains, I think you should not try to drive across the Grossglockner or Silvretta, and take the bus. The new Gerlospass, is an easier one, although on the ride up from the Zillertal, it is still a challange for a novice driver.
I think you mean Lienz (instead of Linz), Linz is in between Salzburg and Vienna. If you need to go to Linz, and still want to drive across the Glocknerstrasse, you can by are return ticket for which you can drive across the Glockner, and go back through the Felbertauerntunnel (between Lienz and Mittersill).
