There's nothing that kills a story—whether it's a novel, a TV show, or a movie—faster than confusing the audience. Stories hinge upon the connection the audience makes with the characters. The moment this connection is broken by a confusing event or action on the part of the characters, or even a poorly transitioned time jump, the audience will start to lose interest.
I've had the opportunity to study this phenomenon up close and personally the last few days, due to some questionable reading and watching choices.
It started with our choice to watch Ong Bak 2: The Beginning. We both really enjoyed Ong Bak: Thai Warrior, and had moderate hopes for this sequel. From the opening, though, we were lost in confusion. We couldn't tell the bad guys apart from the good guys, and the dialog did nothing to help. None of the events seemed prompted by anything deeper or more meaningful to the characters than filler between fight sequences. Halfway through the film, the timeline jumped to the past, only the switch was so poorly done, it took Cody and I several minutes to confirm we understood what was going on in the story. By now, we weren't watching the movie so much as playing a game of who can figure out what the heck is going on first, our connection with the characters—that parts that makes you care about what happens to these fictional people—was nonexistent. That the end was absolutely pointless didn't help at all.
Then we decided to watch Riverworld, a TV miniseries, and the verdict is still out on this one. Watching this with Cody was like a study in plot weaknesses, with Cody as the unwitting detective. Invariably, the moment the plot shifted awkwardly, a character made a strange choice, or parts of the mysterious world were explained poorly, Cody would pipe up with a question for clarification (as if I knew the answer). Cody was frustrated. I was amused, mainly because almost every time Cody would question something, a character on the screen would repeat, nearly verbatim, exactly what he'd just asked within the next minute.
Were this a Hollywood movie rather than a made-for-TV two-part movie, all these question I would think would be ironed out, the plot tightened, so that before Cody was asking for clarification (or at least at the same time that Cody was asking for clarification), the characters would be.
We only watched part one of the show last night, and I'm very interested in the second part, but I think Cody could take it or leave it. While he was confused and lacking the crucial connection with the story, I was pulled in by the mystery of the whole story. I'm more of a fantasy fan than Cody. I like the man playing the main character (Tahmoh Penikett) more than Cody. In general, I'm more willing to suspend my disbelief. But if the producers of the show were relying on all these reasons for the show's success, they drastically limited their audience.
Novels are the same. There's nothing worse than a confusing passage, one that doesn't reveal what the characters' motives are or why they suddenly stepped out of character. (Though, I've noticed it's much easier to have an audience forgive a typically mean character who sets aside their usual reactions to do something nice than it is to forgive an otherwise intelligent character who opts to do something stupid. I consider the latter to be a cheap plot device.)
At no point in reading or watching something do I want to lose my connection with the fictional characters. I'm there to live through their story with them. The moment that I am taken out of the story and reminded that what I'm reading/watching isn't real is the moment that the story loses its magic and dies.