First and foremost the location is excellent. Less than 2 mins walk to the old town square and not much more to Charles Bridge. The apartment is interesting with an eclectic mix of ikea furniture and some antique pieces in the kitchen. Generally quite cool with old fashioned double doors into the sitting room and bedroom and lots of windows. I was just on my own but it could definitely sleep lots of people if needed with 2x double sofa beds in the sitting room and 1x double + 1x single bed in the bedroom. Very clean and well kept.
Not really negatives but some things to note: There is definitely some noise outside especially in the morning, I was woken around 7-8am from some bins being moved I think. Seems pretty quiet at night though, I don't think the street gets much through traffic apart from an occasional horse and cart which is kind of cool to hear on the cobbles!
The bath/shower is just a bathtub with a loose shower head. There isn't any curtain/shower door so I think maybe it's more intended for having a bath and rinsing after but seems to work okay for a quick shower just holding the shower head too.
The mattress on the main double bed isn't very firm which might be a problem for some.