There is actually a funicular that takes you up for an entire 30 seconds to this lookout patio and *surprise* a restaurant. You can look over Salzburg. That's it.
Fun Alternatives: Go up Hohensalzburg fortress. The view is much nicer and at least there is something to do up there other than look at the city.
If you do the carrage ride make sure you get a guide that speaks English or the language of your choice. Ours did speak english but did the whole tour in Austrian. But then he did give us a discount of 50% off after and offered to have one of his friends do the trip over for us in English. (I think he only knew a few words of English)
Unless you have trouble walking, don't waste your money paying for that lift that takes you to the top of the castle. The walk up is tough but you get a great view of the city and the river along the way. Once you get to the castle things aren't that interesting so if you want to save some money, don't pay to go in. Save you shillings for the Shamrock Pub and a few pints.
You can't go far around the old city without walking into the horse carrages touting around tourists or newlyweds