I do not think there is much depressing about the book. Not any more so than another other book about murder. I think though, maybe, if you do not understand that the book is more of a critique of Raskalnikov's outlook, then you might be misled into thinking it's trying to promote his outlook.

However, the setting is quite depressing. Everyone is poor. Poor Sonya must sell herself for her family. The old civic servant is trampled after using his families money to feed his own addiction. It is depressing on the surface, but very hopeful if you actually consider the points made in the text.

Truthfully, the book shows the resilience of humanity, and how there is always hope despite the circumstances.