Every time I visit Krakow I go to Massolit to look for books that I would just not find so easily anywhere else. The café is old and worn but very very comfortable, the coffee is good and although I have never tried the tea they seem to have tea for all tastes. The food is usually good although I have had one or not quite up to scratch pastries. It's not a place to have a meal, just a snack; cheesecake, raspberry tart, apple pie, quiche, and similar things.
You can read the books while drinking your coffee, put them back on the shelves if you decide they are not for you.
The staff are very helpful and the wifi is pretty good.
For me I would say the only thing I really dislike is the jazz background music. I would much rather have something baroque or from the romantic period, or even some rock.