My girlfriend and I went to Wierzynek on our last night in Krakow as a way to say goodbye to the city. It was a wonderful experience. The food was very well prepared. We had rather exotic dishes: wild-boar roast for my girlfriend and a veal steak with wine sauce for myself with soup and salad. It was delicious! For dessert I would highly suggest their ice-cream with fruit and liquor medley. Decor was simple, but very fitting; service well-attired and polite.
Note on prices: while this restaurant would be completely out of the range for an average-earning Pole, it proved to be amazingly affordable for a couple foreign tourists like ourselves. For your information: our total bill came up to 187 zlotych (at the time's exchange rate that came up to $46). At $23 per person we each had: a soup, main dish, dessert, soda, cappucino and a beer. Being a lover of fine-dining I call it a bargain!