Topas Hotel is located only a block from the Frankfurt Hauptbanhof, making it very convenient in terms of arrival and departure by train or plane.
Our very large double room was on the ground floor facing the street, meaning we didn't have to drag our heavy bags far - a bonus after a month of travel! We could hear some voices on the street outside, but not traffic noise. I've come to accept that completely silent hotel rooms in Europe are not the norm!
It was snowing heavily during our visit, and the temp was -8 degrees. Although there were heaters under the window and in the bathroom, I noticed that the window didn't seal tight and thus there was cold air creeping in around the window. It wouldn't have been an issue in less freezing weather.
Breakfast was quite good, with a reasonable selection.
We made use of the free Wifi to check our departing flight status.
Beds were clean and comfortable. The bathroom was larger than most in Europe and had shower over the bath.
The neighbourhood was not seedy at all despite its proximity to the rail station and we felt comfortable making the 20 minute walk into the Altstadt after dark. All in all we have no complaints, and would definitely stay here again.

My husband and I stayed at this hotel for just one night when we were flying out of Frankfurt after spending a few weeks in Germany. The location - near the main train station - is super convenient and the hotel is easy to find.

The staff was professional and friendly, the breakfast (included) was great and they even had free wifi which was a plus. The room was quite large and while as noted by others there is no AC they did have a fan in the room and the windows open. The bathroom was also quite big with a tub/shower that is big enough for a soak (not for big guys of course), had hair dryer and plenty of towels.

There is lots in the neighborhood and it's central enough to walk to Romerburg Square or just hop the train and you are there in 2 stops.

The price was great (I think we paid $58 Euro) and it was better than others we stayed at for twice the price. Yes - it's a little loud on the street at night but hey, you are in a city and that's to be expected.

I'd definitely stay there again if I was in Frankfurt.

We spent a weekend in this hotel with friends and we were really satisfied. The location is very central and safe, the city center is within walking distance.
We had rooms on the streetside and they were a bit loud despite the double-glased windows. But it was okay. As people already mentioned before, the rooms don't have air-conditioning, which can be disturbing during a hot summer day but in the autumn it doesn't matter.
The breakfast was fine but not extraordinary. It was good enough to start the day well.

The hotel is located two blocks away in a street parallel to the main railway station. This means it is ideal for catching an early flight/train or when arriving in Frankfurt late. It therefore has excellent connections to the airport and also to the trade fair area and the town centre. The hotel is obviously well-established, possibly a bit tired-looking compared to other hotels, however it is very clean and well-looked after. The hotel does not have air-conditioning, although the room I was in did have a fan. My room was to the front and this road was fairly noisy in the morning from about 7 o'clock. Breakfast in the hotel was simple but perfectly adequate.