Finish it, or use it as a coaster? Shakespeare would be able to couch this more elegantly. For my part, I imagine the debate between finishing a mediocre book or chucking it for something else a lot like an old fashioned cartoon, in which an angel and a devil are perched on either shoulder, playing tug-of-war with my literary conscience.
Currently, I'm slogging through a book (which shall remain unnamed). Slogging, here, isn't hyperbolic, unless you're envisioning me in galoshes in a swamp, which so far hasn't been the case (unless we're speaking metaphorically). At night, I turn to look at my nightstand and gaze at the stack of graphic novels and beach reads beckoning, revisiting the pages of my current book with a sigh and an ever-weakening resolve to finish this thing, once and for all.
Unlike a lot of issues that provoke some sort of ire or anxiety in me -- voting, adopting shelter pets, and female characters in young adult literature, for instance -- I see the merits of both sides here. Would Faulkner's Absalom, Absalom! lie on some table right now if not for this persistence, untouched except by the bottom ring of a coffee cup? Would I be able to chime in on the Twilight series or The Hunger Games if I hadn't read the first volume of both series front-to-back, thoroughly, even though both of them felt problematic in certain ways? There's certainly something to be said for commitment, particularly when the material is more complex than your typical fare or culturally important in one way or another.
That said, it's murkier when the novel in question isn't a Modern Library Edition, a certified classic, or the next sleeper hit of the summer. Of course it feels good to finish The Red Badge of Courage or Brave New World, even if neither rank in the top 50 on your Goodreads queue. At least you can say you've read them, and you can apply those ideas to everyday life even if the prose or storytelling didn't grab you. The same can't be said for an obscure, unknown title or fledgling author, even if they're lauded as the next coming of Herman Melville. Only time can brand something as a part of the canon, and in an age where marketing and PR gets its grubby fingers on everything from the author's Facebook page to their book jacket, the conversation trailing a new release isn't a reliable indicator of its actual merits or significance.
As a writer, this conundrum reduces to a simple equation: if people don't care, they won't read it. Most people aren't foolish enough to suffer this sort of crisis for the sake of literature. Most people would pick up a book, read 20 or 30 pages, and move on to the next thing, because life is short and there is an abundance of books within your physical or electronic reach in any given place.
A little insight, while still maintaining whatever shroud of mystery I had going on before (feel free to LOL): the book I'm reading now is a jolt from my usual genre preferences, has been highly praised by critics, and is one of the author's first endeavors. It's rather lengthy, and I'm already more than halfway through.
Finish it off? Abandon it for something more compelling? I know what I'll probably end up doing, but you wiser souls should tell me what you think.