So I've read The Hobbit, and I just finished reading Lord of the Rings. The other popular book I've heard of by J.R.R. Tolkien was The Silmarillion.
So to my question: I've heard some really mixed reviews of The Silmarillion, is it worth reading or should I go on to something else?
Also, if you wouldn't recommend this book which book would you recommend?

Why not give it a try? Get it from the library so you won't be buying it.

Have you read the Harry Potter series?

Never listen to reviews it's a good way to miss out on a book that you might have loved. I agree with wonder girl. Borrow it so if you don't like it you won't loose anything. As far as suggestions go you might like The sword of truth series by Terry Googkind Or the Inheritance series by Christopher Paolini.