 Nothing really everything was very nice and a very good price I ended up staying an extra night and they honored the price I booked my room from booking com 
 Loved the whole atmosphere of hotel So convenient clean wonderful staff great breakfast excellent wifi Bed was very comfortable shower temperature and pressure outstanding Also there was an almost 24 hour coffee room which had cappuccino machine teas and some snacks It was all free too I would highly recommend this quaint and lovely hotel for a stay in Vienna 