Great place! Well-prepared and clean, kitchen worked well for our week-long stay, we had everything we needed! Location is close to public transport and to the central station, with quite a few stores around.
No smoke detectors - one was in a cupboard above the fridge, but not fitted. In winter, it can get cold; thankfully, there's a heater available. The shower room is a bit cramped, though, has everything one would need.
Can absolutely recommend, and will be looking out for this place next time I'm in Vienna!