For more than six years, I use the main train station in Frankfurt regularly.
There is a lot of train traffic. Constantly trains roll in and out. The corresponding values I've picked out of the home page of the DB.
* Long-distance trains per day: 342
* Transport trains daily: 290
* S-trains daily: 1,100
* Travellers and visitors daily: 350,000
That's a lot more than I know from "home".
If you come to a long-distance train, so I do, then you find yourself in level "0". If you want to be continue for example on a local S-Bahn, you have to go down to "Frankfurt tief".
Before you reach it, you will see a lot of stores and restaurants. In addition to the large station bookstore, there is a food market. As well stores of Tchibo, Mc Donalds, Gosch, Mr. Clou, Fresh Company, Häagen Dazs, Sandwich & More. Only a small selection of all what you can find.
This station has a "travel agent at the station" (this travel agency chain currently has 32 stores in Germany).
Of course there is in the main part of the station a big DB travel center and a lounge for 1st class passengers.
A while ago I had to left luggage. And it was a big bag which required a correspondingly large locker. The storage costs about EUR 6! Very expensive! Yeah sure, for that price you can "park" the luggage for 24 hours. But I needed it but only for about five hours. And a "short-term rate" is unfortunately not available.
Overall, the Frankfurt train station offers a pleasant atmosphere and makes a clean impression. I never noticed something seriously wrong. However, sometimes the beggars might be annoying.
There are lockers at three locations.
Modern toilets available of the chain "rail & fresh". These are open around the clock and offer female and male toilets and also showers.