I have to say that it is worth the stay for the amazing 360° view of Krakow from the terrace and I believe that that's what I paid for.
Also Agata from reception was extremely helpful and great.
Now the negatives:
The check in process was poor, no message with instructions or email, no response to Expedia messages, I was stressing out flying from abroad late worrying I won't be able to check in at night. I asked my sister in Poland to call them and she advised messaging on WhatsApp which helped and the communication was very easy then. The floor in the flat was absolutely disgusting, dirty, gritty and lots of hair crumbled together and dust. There was dust on shelves, skirting boards, behind the bed and sofa. We wore our pool shoes the whole time, otherwise our feet were black. The side table under the stairs was sticky from drinks, the kitchen towel had a long black hair stuck to it and so did towels, there were hairs everywhere. The terrace upstairs had a cigarette bin full of them practically falling out and a beer can inside. The bathroom could have done with dusting too, plus badly designed without towel hooks and toilet paper rail too far to reach.
Kitchen is OK but no oven or microwave, no kitchen towels or anything to wipe the counters.
The bedroom had twin beds set up despite a booking for a marriage and a child. There's also no door lock from insido so it made me feel a little self councious about safety and privacy. I'd say install at least a door chain.