The hotel is very central in Frankfurt. Very close from Main train station, city centre, BCE.
The hotel is clean and service is excellent.
The hotel surroundings are a bit surprising with sex shop and clubs.
The room I got was very quiet (although on 2nd floor), the bed is good, quite small and on overall quite old (the refresh was partial). The surrounding and the overall hotel quality, in my opinion on a low range for claiming 4 stars explaining the average rating.

A good hotel with very good staff. Quality of service is very good and staff is very caring
Location is KaiserStrabe, which is main street in front of Hoptenbahnof.
Breakfast was very good.
On top they provide bar services free of charge. You can have gas water, fruits and hot drinks 24 hours at the lobby. Wifi is free and best because on a business trip you must need this. Overall hotel is very good.

OK - I am not a fussy person, but getting any explanation or help from the evening/night staff was a joke: barely speaking English, doing everything as they want it: at check in I could get any explanation why they want my credit card when they had company's card details. I found out on the following day that the company card did not work.
Asked for password to the free internet in business corner - got SOLD 3 hours of internet for EUR6! Without asking if I want to pay! I wanted to buy water from the vending machine: it didn't work. Was told to take it from the minibar.
Day sataff: young, helpful and communicative.
I wouldn't return. Couldn't relax after busy day. Rooms need updating. Especially carpets and bathroom.
It is all working and acceptable, but not as smooth as you'd expect it.
Location was good: close to train station. But a lot of weird guys walking around in the night, drinking.
'Australian' restaurant Kakadu across the street was nice.