Alright this was so!!! cool!!!
Before reading I only knew that there are letters in it and that it's sci-fi, so I really wanted to read it cause I like both of those things. And this book gave me SO much more than I expected, I can honestly say that I loved it and that I'm gonna think about it for a long, long time. Although I think I need to read it in english some time in the future to compare with its polish translation.
Also the ending – ?!?!?! I actually love when books do that (no spoilers though and don't try to look them up before reading).

PS I got this book as a gift from the coolest person in the world and both the book and the person get some extra coolness points because of that