I spend there 4 days during a training, we had breakfast and lunch pre-paid, no dinner was possible. I will just list my observations:
- food is fantastic, especially the deserts
- rooms (at least in one part of the hotel) are really tiny
- there is a very nice garden attached to the hotel
- there is a bar in the hotel, where smoking is allowed, the smoke then fills nearly all of the hallways and lobby

We had a four person family pair of rooms on the third floor (310). The room was functional, clean and relatively spacious, with a walk-in wardrobe, large bathtub and free fast WiFi. One room had a large double bed, while the kids slept in a fold out sofabed adjoining it. Breakfast was a generous buffet with a good selection of hot and cold options. The hotel has a garden with duck pond. The hotel staff were very friendly and spoke good English. There were only local channels on the small tv in the room. We bought 72 hour Vienna Cards from the reception which entitled us to free public transport and various museum discounts.

The Schunbrunn Palace is a 2.5km jog away, whilst the Am Shopwerk U-6 station is a few hundred metres away.

Nice hotel and good value, if out of the way. If coming via Vienna's excellent U6 line, be sure to print out a map from the station to the hotel - it is about a 5-8 minute walk and the locals may not know where to point you. Excellent breakfast buffet. Restaurant is pricey - strongly recommend the wine bar Heuriger 5er Pflug - http://www.pflug.at/ around the corner for a good, local atmosphere meal at a much more reasonable price. Very helpful staff. BTW, the garden creates a nice atmosphere, but it is not nearly as scenic as pictured on the web site.

Gartenhotel smells of smoke. This isvery noticeable when you dome from smoke free countries. Even the non-smoking rooms smell of it.
The rooms are comfortable but dated and need some fresh paint. The beds are comfortable but I have been woken up and some have my colleagues, but strange mechanical noises at night.
The staff are friendly but only moderately attentive. Service at the bar is slow, reception OK.
Breakfast is OK but don't expect a wide range of hot foods.
If you need to stay here for business for a night then it's OK, otherwise look elsewhere.