I was there for 4 days. 3 of them in bed, near death with a lung infection. The last night I got on the piss hard. Staying at a party hostel and it was their 5th anniversary. So much vodka!
But yeh, nice city with good nightlife. Auschwitz is an hour away. Haunting but worth a visit. Don't go to Krakow on a public holiday if you need a hospital though, everything is fucking closed!