Let's start with the great things:
Location! Just a few blocks from Old Town Square. You can't beat the location for the price!
Water pressure and removable shower head. This might sound silly, but do you ever stay at a place that just dribbles on you such that you don't feel clean?
Microwave! C'mon Germans - this is a great machine! You can't eat everything, so how can you heat up leftovers? Microwaves rule.
Washing machine. Wouldn't have stayed there without.
Less than optimal, but not really something Jan & Sarah can do anything about:
Crying babies. And arguing neighbors. But that is what earplugs are for.
No comfortable place to sit. The place is arranged to optimal space usage, so there is nowhere to add a good chair. But who goes to Prague to stay in their room?
The windows open up to the complex's garbage cans. We didn't have a problem with any smell, but if you're going for views, this isn't the place.