When you really think about it, all decisions really boil down to one of two choices, don't they? Every battle is decided based on those two choices. And as an author, you have to decide which you'll use to introduce your plot points: action or dialogue?
One for the Ages
It is truly an epic battle that is waged on every page of every manuscript ever written. Should you use the spoken word to convey that piece of information, or a scene involving actions instead? Should you blend the two together into one multi-layered scene? And if so, how? Action vs. dialogue is a never-ending struggle...and I've noticed one common thread among the authors who find themselves losing that war.
You can't ever let dialogue win. If you want to win this war, then you must embrace the fact that action must be your champion. He's your Achilles, your David, your Russell Crowe. Dialogue is a scrappy little fighter, and it's fine to let him win a few battles. But action is going to carry your book, and it's going to eventually win out. Otherwise...well, you're going to have a pretty boring book.
If you use dialogue to convey every important plot point, I guarantee you I'll get sick of it before I even get to the fourth chapter. The bad news is that I'm a more patient reader than most. The vast majority will give you three pages to grab their attention at best.
Dialogue is good sometimes, especially if it's funny or dramatic. Seeing two characters exchange quips (or even better, insults) is amusing for us all. Seeing two characters share deep, dark secrets is captivating. But I don't want to sit through a dozen different conversations that are all essentially the same only to learn some new tiny tidbit of information each time.
Information can be, and should be, revealed in other ways, too. Characters can discover diary entries, or photographs, newspaper clippings or clothing that reveal something about another character. How about seeing something in their purse, watching something fall from a pocket, or tripping and falling and accidentally discovering something they're hiding under the bed? All of these are action scenes, and good writers can make them sound interesting rather than mundane. Better yet, it's relatable. I've fallen before, and while I haven't necessarily discovered a dark secret for doing so I definitely felt the thump. So I'm going to emphathize with a character who falls, and what's that under the bed? Let's examine this evidence right now!
I'm excited, I'm engaged, and I'm reading you story because there's action in it. Remember that an action scene doesn't necessarily mean the swords have come out and now we're fencing. An action scene is any scene that involves moving. Walking up the stairs can be an action scene, if something happens on that staircase. A trip and fall can be exciting and a little dangerous, and no one has to bring a sword to the party to make it that way.
So don't let dialogue win your book...or you'll wind up being the big loser in the war.