For many years I have fallen on the “no, I do not have to finish a book” side of the argument. My reasons are that there are so many GREAT books out there that I won’t waste my time with ones that don’t hold my interest.
However, there was recently a great blog post over at the Rabbit Room in which Pete Peterson talks about his reasons for plowing through. You can read it here.
So, your chance to weigh in: do you have to finish a book once you’ve started? Why or why not?
Related post:
I miss reading.
JACKIE LEA SOMMERS 
I’d say it completely depends. If a book’s premise or core character is misguided, I think letting it go could be the right thing to do.
Daniel
My reading time is to precious to me to waste on a bad book. If I’m having doubts about a book, I’ll give it a few chapters to convince me to keep it, then I stop. I’m much harsher about buying a book
I have to know how it ends, so if it can’t hold my attention, I skip to the last few chapters and skim to see how it ends.
i have to read a book all the way through, what if it gets good at the end, like Jellicoe Road (i was uber confused and you kept telling me to keep reading!!!)
Ahhh, but see, Jellicoe was good writing ALL the way through, even if the beginning was confusing!