Hopefully reading is an exchange between world view and the world viewed in the book. If we enter reading convinced this book is a waste of time (an assignment perhaps), it often becomes so. If we enter reading suspecting this book is a waste of time, it might surprise us. Books can change your world view if you let them. Critical reading allows us to make our world bigger without blindly accepting the words we consume.
An examples: For some reason I wouldn’t read Vonnegut. Perhaps the person who most recommended him was someone I considered superficial, perhaps I had an adverse reaction to a line someone recited. It wasn't until a professor whom I didn’t care for made us read Breakfast of Champions that I discovered I loved Vonnegut and that this professor may have more to offer than I previously assumed.
Vonnegut’s writing profoundly influenced mine.