I stay at this hotel every time I come to Frankfurt on business. Non smoking single rooms are renovated in 2010.
I stayed 2 times in X01 (like #301, #401, #501) which I found roomy compared to other single rooms but #X01 room has no bath tub, but just shower room.

3 minute walk from the central station and 10 minute walk to Opera and the convention center.

What I like the best about this hotel is breakfast. Their original oatmeal porridge is excellent and you can also have various kinds of cheeses, hams, breads, juices..

Hotel is located within a 10 minute walk of the Hauptbhanhof. Check-in was fast and staff friendly. Room for a single is very very small, single bed, small desk with small TV and a nice bath. Free wifi is included however breakfast is not and is a pricey 14 euros. Walls are very thin, and one can here the guests next door. Good for a one or two night stay.

The prices we found to be quite cheap. It is located just a 5 minute walk from the central station which is very positive, so it is very easy and cheap to get to from the airport with the S-bahn. The negative thing with the location is that it is located just outside the red light district. We still found this quite OK, since you could choose to take a longer path and walk around that district. However, the area attracts some drug addicts and other suspicious people. This is actually the only major downside with this hotel.

Otherwise we found the hotel staff to be very friendly and helpful. Free WLAN, which however was quite slow. The breakfast was good, but nothing extraordinary. I found 14 EUR to be a bit pricey, but I guess this is a normal hotel breakfast price. We were upgraded to a Comfort Room, so I don't know anything about the standard rooms. Anyway, our room was nice and clean and the beds were very comfortable. It seems only the comfort rooms have air condition, but not the standard ones. The room was not very big, as in the USA, but there was enough space. I would say a standard European size. The bathroom was clean and modern.

Well for 50€ this hote is a good deal. The room is adequate for a three star-hotel. You get free internet WLAN. There is lots of space in the lobby and wide of range of newspaper in the breakfast room choose. The room was adequate for three star hotel. The downsides. The bed was not very comfortable and location near the main train station is a major disadvantage. The area around the main train station is the red light district of Frankfurt and is now to be frequented by very seedy individuals. First time in a long time in Germany where I did not feel safe walking around at night.