Along with the entire city of Salzburg, the fortress is a must-see. The fortress stands over the town and you can't help but want to take pictures of it. You can also go to the top to see some great views of town. After the cable car you have to climb a while, and you are priced with the magnificent view.
The self-guided tour is very well done, with a lot of helpful information. They do a good job of describing the history and various tactics used over time, and you're left with a real feeling for what life might have been like when this fortress was used. Highly recommended.
Photos taken with Sony DSC-HX50B.