Putting down a bad book

Some astute readers of my blog (I think a total of two people) might have noticed I started reading a new book but didn't put Dan Brown's Digital Fortress in the "Just finished reading" section. I liked DaVinci Code even though it read like a screenplay - it was fun. However since I am in computers I couldn't stand all the little mistakes Dan made in Digital Fortress. Furthermore after reading DaVinci Code, which came after Digital Fortress, I felt I already read the book. I asked a good friend at work about this. I basically said - "Is it alright not to finish a book" to which he replied that yes it was. He told me earlier in his life he couldn't stop reading a book even if it was bad but now that he is older he will just put it down. Life is too short for bad books.