Great hotel, well located and fuss-free check in and check out. I arrived late at night and it was super easy to find the location, access the key machine and get into my room.
The only down side is that there is no air conditioning other than opening the windows which have limits on them, so it was rather warm due to the heatwave. There was a large fan provided which was effective, but quite noisy to use in the night.
The in-room drinks (water bottle, coffee sachets) weren't replaced when the housekeeping came each day which was a bit odd, but otherwise it worked perfectly for a short business stay in Vienna.