We had a great stay in Vienna! We were 6 colleagues there for an international conference (at Vienna International Center). The flat is big enough, very clean and well situated at proximity to the river, Augarten (Big park) and we were at 25 min walk+subway to the conference center. The access via lock box is convenient.
Only small inconvenient is that we had to pay extra fees (40€) for city taxes and it was not mentioned in the ad. I would have prefered to have it included in the first payment.
Cheers,
Julien