We've spent two nights in Filip's apartment and for us it's a 10/10.
The apartment is very clean and new. It has everything to offer one could need during a stay away from home. Filip and his family are very friendly, supportive and helpful and check-in and check-out were very easy.
It's located in Mala Strana and thus all of the main attractions are in walking distance. Charles Bridge is 2 minutes away.
We highly recommend a stay in Filip's apartment, you'll enjoy it.