Yes, Dostoevsky is a great writer. My favorite in absolute was Crime and Punishment.
Do you recommend reading it?
I would say yes. Gray's book is good stuff. It's not an easy reading, but it's really good stuff. I don't agree with a lot of parts of the book, but his way of thinking is very interesting. I think John Gray is a nihilist in his way of thinking, but his criticism against modern politics and political religion is very sharp.