The acting in Jaws is not awful, it's absolutely excellent. Robert Shaw and Richard Dreyfus are Great Actors and they deliver the goods here - and Roy Scheider ain't half bad, either. Jaws is one of those films that in repeat viewings provides its thrills through the way the actors deliver their fabulously well-written lines - sod the shark, the way Shaw enunciates 'a doll's eyes', or even the way he just nonchalantly throws the life-saver to Brodie as the boat goes down are just ELECTRIC. You can take all your hypothetical 'oh- wow' cg shark effects and shove them, they're worthless compared to that type of acting presence.
And the fact that there's not much shark in Jaws makes it better, in my view, than all the monster-filled cg fests we have today. Despite its wobbly shark effects, one of the great things about the film is nevertheless its effects. i.e at least they contain no irritatingly bad cg and no irritatingly bad virtual camera motion, one of the banes of modern Hollywood. The other banes of modern Hollywood are lousy acting, phoney dialogue and fluffed tone. Directors should be made to watch movies like Jaws every day with their Cheerios before they start work so they might get a clue again as to how to get this stuff right.
But this is not to say Jaws is High Art - as Deathstalker has been keen to point out. It's not Vertigo, and I don't think anyone here is saying it is. It's a pulp-paperback-about-a-shark movie adaptation, whose terrific ensemble acting, fantastic dialogue, utterly brilliant directing and perfect tone just happen to make the viewer easily mistake it for a Great Classic.
Me, I much prefer Jaws to Raiders of the Lost Ark. Because the characters are far more interesting, and all the situations are far more engaging. And because it has Shaw's self-written Indianapolis speech in it and Raiders doesn't.