When the game Metro 2033 came out a few years back, I played it for like an hour. I wasn't really good at it, and it had too much horror elements for my taste. Despite those reasons, I really liked the setting of the game. That post-acolyptic undergroundish envirnoment had something... intriguing. So, after I read a bit more about the game, I discovered it was based on a book.
Some time later, I came across the book in a bookshop. Without thinking, I bought it. I didn't start reading right away, but when I did, I was hooked.
I loved the way the world is described. That dense, dark world not bigger than Moscow, where all living people lived. Although some conversations were a bit long - some spanning multiple pages - it didn't bother me at all. Glukhovsky put some very interesting theories in these conversations. About (the meaning of) life, religion, the reason why people act the way they do, etc.
Although I loved the worldbuilding and conversations, something I still can't describe was missing. Something that was slowing my reading pace down. In the middle of the book I had to push myself to read further. That's why I gave it 4 stars, and not five.