My other half has just been on a stag do to krakow. He said it was a nice place and I do know its very cheap!!!. They tended to stay and drink in the main square as its full of bars. He did say that the local police dont really like big groups of lads and some places probably wont let you in if there is a.gang. All in all, a nice place.
i's a very pleasant place... regrettably, the stag parties (and hen parties) are one of the drawbacks. It's pretty cheap and has lots of history, should you have any time off from drinking. You can even visit Auschwitz.
It's a superb place, very cheap, good food and the accommodation, even the cheaper stuff isn't bad.
Although if you look on trip advisor at some of the cheap hotels and hostels, some tourists have been robbed whilst drunk. Gypsys begging are a problem and whilst I was there last October , a woman was mugged in the Main Square.