I've lost count of the number of ground-breaking screenplays that use voiceover. Off the top of my head, here are a few:
Joel and Ethan Coen movies:
The Big Lebowski
The Man Who Wasn't There
No Country For Old Men
A Clockwork Orange
I'm sure there are plenty more if I thought longer. All of the movies on this
list are outstanding, most now modern classics, and many are multi-award
winners. Their writers and directors quite rightly didn't bother worrying
whether voiceover was something the gurus frown on.
Of course, these movies are stunning examples of cinematic originality, and there are plenty of films where voiceover just creaks with embarrassment-inducing clunkiness.
Whether you think voiceover is just a question of laziness on the part of the screenwriter is up for discussion.
Voiceover is an element of exposition, and is one way for your audience to get inside your character's head. But you'd be a rare genius to get away with this for the whole length of a movie.
Exposition - finding ways to externalize meaning is one of the biggest challenges for a screenwriter and is probably what makes it most difficult in comparison with novel writing..
I've just been writing about this dreaded problem of Screenwriting Exposition which every scriptwriter has nightmares over. It was something that I always found really difficult when I started out writing scripts.
But once I put the How To Books back on the shelf and trusted my intuition, I began to realise that exposition isn't just about getting facts across to the audience, it's how you communicate meaning to your audience.
And instead of dialogue, you can use visuals, atmosphere, climate, the weather, sound, even the clothes your characters wear. Exposition became something that fired up my imagination instead of being a mechanical chore. So I've been coming up with ways (I hope) to get my students and site visitors to learn to love it.