It's clean, close to the Westbahnhof and the breakfast is OK. There is also a tram stop just around the corner which makes for easy travel around Vienna.

Hotel is located about ten (15 in our case!) minutes walk from the train station - or you can catch trams E or U (Kaiserstrasse) from outside the station which take a few minutes.
Looks a bit drab from the outside. Staff were not overly friendly but did help us when asked for directions/transport etc. They also accommodated us when we needed to leave our cases for a few hours before out train journey.
The centre is apparently a 25min walk (we never did it) but instead we caught both the tram (which took us near to the back of the Spanish Riding School and we also used the underground which was quicker and came right out by the cathedral (Stephanplatz). We bought a 24hr ticket costing 5.70E and that covered all modes of transport (but alas, was never asked for!)
Our room was large, with air-con and a fan, and a big fridge. This was amazing as it was 37 degrees when we stayed!
Beds were comfy (something they use in Austria makes them so!) and there were complimentary slippers and toothbrushes!
There was a large variety for breakfast which was of good quality.
Overall, I would stay here again because of the value, although I would prefer something closer to town.

The rooms were lovely, clean and very big!

Free, high speed wifi was a great bonus and breakfast was also good.

Location was just around the corner from the train station and tram line which will take you everywhere. Or even better (and much more fun): hire a bike from the local bike rack outside the train station and ride! Very easy with all the bike lanes around town.

We booked Hotel Kaffeemühle for 3 nights and arrived at the hotel around 4pm from Prague. We walked to the hotel from Westbahnhof and it was conveniently located. I booked this from Lastminute.com and the location of this hotel on their map is wrong. This has happened to me before, so luckily I checked it on GoogleMaps to get the correct location.
The staff was very friendly and we got our room on the 2nd floor. The room was bright, clean and spacious. The hotel is located about a 20-30 min train ride from the city centre. This is no problem as public transport is very frequent and reliable, a 24hr ticket costs 5.70 Euro. Westbahnhof station is only a 10 min walk from the hotel which connects U3 and U6. The room seemed to be newly refurbished. The bathroom looked newly tiled and everything was very clean. The hotel room had a mini fridge and LCD TV. The breakfast was very nice, cerals, toast, rolls, hams, cheese, tomato etc, with a great coffee machine. They do have a free WIFI service. The internet is very fast.
There are eateries all around the street, or you can walk to Mariahilfer StraBe in about 10 mins which has a lot more shops.
Would definitely stay at this hotel again. Great comfy rooms and breakfast at a very good rate.