We stayed at Leonardo Hotel City Center during our business trip at Heidelberg. The hotel is very well located, close to city center, the Campus, many parking lots and some green parks around which is nice. You can find very good restaurant and bars options nearby (La Vite, Italian restaurant, is excellent).
Rooms are clean, big and confortable. No noise issues especially when you are directed through the court.
Only negative: no shower cabinet, a tiny bath instead.
The reception hall is wonderful with many seats, some fresh water and candies. Staff is mostly highly welcoming.
We took the breakfast option. It is quite a high price and we didn't enjoyed as much as we expected. Nevertheless when weather is ok, you can have it outside on the terrace which is so relaxing.
I would highly recommend compared with the other hotel I've already been in the same area.