piderman: Gry Online (Polish) gives it a 9.5.
Google translated pros/cons:
PROS:
addictive, well-told, non-linear story;
intransigence and attention to detail;
superb dialogues;
variety of side quests;
beautiful graphics and visual art;
scalable difficulty level - everyone will find something for everyone.
Cons:
the end leaves a huge unsatisfied;
minor technical issues.
If I read the "translation" correctly, the game ends very suddenly and does not have an 'epilogue' like Fallout: New Vegas or Dragon Age have. Other reviews have alluded to this as well.
added also translated more true ti source.