Salzburg is beautiful, the people are (generally) friendly, and there is plenty to see and do for about two days. We spent three days ithe city and it was too long.
Old Town is picturesque and has a cozy, old-world feel. It's walkable, but crowded because of the narrow streets and many shops. Restaurants tended to be pricey even for basics such as pastas, sandwiches, and pastries. Pretzels are a great deal, though! Dinners always seemed to be 3-4 euros more per entree than you'd pay in Munich (about 2 hours away by train). Be aware that much of the city shuts down by 7--even on the weekend.
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