1. It's fascinating. 2. It's intriguing. 3. I couldn't tear myself away. 4. I couldn't put it down. (this phrase is used for en extremely interesting book) 5. I was so into it, I lost track of time. 6. It does nothing for me. 7. I was bored to tears. 8. I was bored to death. 9. I was dying of boredom. 10. It's about as exciting as watching paint dry. (= it's very boring)