My wife, daughter and I really enjoyed the apartment. There was plenty of space for us, which isn't true of every place we've stayed at on Airbnb :-) The location is terrific, with plenty of interesting places to eat nearby. There is a fair amount of foot traffic and noise in the evening, but the street facing window is two double-paned windows, so once they were shut, it was like being in a quiet neighborhood, so no issues at all with noise.
If you are looking for an apartment in a location with an old European city feel, you can't beat this apartment. Lots of narrow, winding, cobble-stoned streets, and only a few minutes from Charles Bridge and the old town square.