Short answer, yes and no. I saw some tweets the other day in reference to cliffhangers and not being overly fond of them. The reference here is I believe, specifically to the case of series books ending with some kind of “oh, my god” moment, leaving the reader to find out with the next installment what happened. This is in fairly sharp contrast to using them within the confines of the cover of one book.
In general, cliffhangers are a device used to keep people reading, to put you on the edge of your seat, and always keep you wanting to find out what happens next. This can run the gamut from the emotional to the physical. It can be very subtle or highly dramatic, and if done well, are quite effective in managing the pace of a book. You obviously do not need someone on the verge of death at the end of every chapter to keep reader interest piqued. I’d go as far to say the sublte cliffhangers are more effective. If one is invested inthe characters of a story, leaving one wondering about an emotional development is more compelling than wondering if the bomb is going to be diffused on time.
So, we’ll assume here that utilizing cliffhangers within the pages of a story are good, effective, and desireable. But what about the dangling moment left at the end of a novel, where one must then wait months to discover what happened? Does this honestly keep the reader anticipation built up, hungry for the next story to continue so they can find out the results of that dangling thread? Or, does it merely leave them frustrated and annoyed? Personally, I don’t like this “left hanging” ambiguity. I don’t desire to be left frustrated with an unresolved penultimate moment. Because really, if the book did not stand up on its own to build my interest and invest me in the characters, I would not care anyway. I’ll also read other books in the meantime, the anticipation will wane, and my interest will decline. When that next book comes out, I’ll be like, “Oh, yeah, that character was about to die.” The only time this really works for me, is when I have the next book handy to start right after the previous one. But leave me waiting? Not so much.
In the end, the cliffhanger is, for the most part, useless. If I enjoyed the first book, I’d be reading the next whether there was a cliffhanger ending or not. I don’t need to be frustrated or left wanting in order to buy the next one. If anything, it’s likely to deter me. This isn’t to say however, that stories can’t leave dangling threads, unfinished character arcs, and plotlines that would be continued. In a series this is to be expected. These are cliffhangers all on their own and entice me far better than the cut0ff penultimate moment at the end. Writers, don’t feel the need to do this. It’s a waste of time, and if you feel compelled to do it in order to keep readers interested, than there is something lacking with the rest of the story.