I don't understand Polish, so read it in English only, and enjoyed it very much. As I had no possibility for comparison, as purely a book in English, I didn't notice any problems with the translation at all, and it seemed perfectly idiomatically correct.

If other posters mean that the translator did not "Americanise" it : -um, well that is what I would want and expect.
I would expect it to retain at least some of it's Polish flavour, I wouldn't want a completeley "USian" book, sanitised amd stripped of its original flavour, the way that they did with the US version of the game.