We had a nice stay at the Hyperion but it could have been a bit better. The initial check-in was slow. Our room was nice, but seemed to be in an out-of-the way corridor of the hotel, which is an old palace. We stayed for 2 nights. Arriving back after our first dat of sightseeing, our room had not been cleaned although it was past 4:30 pm. The front desk told us they had till 5:00? There was a food cart in the corridor from room service that had been out there all day.
The breakfast was wonderful, probably the best we have ever had at a hotel. Would have been wonderful anywhere.
The staff, overall, was friendly and helpful. The location is close to Mirabell Gardens, which are actually on the edge of the touristy part of Salzburg, so the hotel itself is not really in the tangle of the busiest tourist areas to be sure. There are some nice restaurants near by.