Centrally located, clean and quiet! Breakfast on the patio is fantastic, and the tiny pool on the rooftop is incredibly refreshing. We stayed for three days - Tues, Wed, and Thurs - and were incredibly pleased with our room and the staff, all of whom were super friendly and helpful. (We speak minimal Spanish, but all of the staff speaks some English, and at least two of the staff are fluent, so it was no problem.)
One of our favorite things to do for lunch was pick up an assortment of fruit and empanadas from the local street vendors and eat lunch on our balcony, overlooking the park below. Gorgeous!
The room had AC but we never needed to turn it on - the fan and tile floors kept the place cool and comfortable. There's a little noise from the park and cafes below at night, but that's part of the charm of the city.
The location is great - Cartagena is a magical city and Casa La Fe is a perfect base for exploring it.