I accept that Mr Costner does not have the screen presence of a Bogart or a Bogarde, perhaps even of a bogie, but this does not diminish the wider point: Waterworld is an excellent film. This is a fact.
I accept also that his oevre contains some stinkers (almost every other film he made), but this too does not detract from the wider point: Waterworld is an excellent film.
Any merit attaching to JFK, The Postman, The Untouchables or that baseball thingy is despite Costner rather than because of him, but this does not detract from the wider point: Waterworld is an excellent film.
If you can name a better film in which a partly-evolved amphibian human, an orphan, her guardian and a strange Hungarian balloonist battle the forces of evil, as led by Dennis Hopper on their rusting oil tanker, and ultimately prevail despite a series of devastating setbacks and acts of perfidy by said baddies, I'd like to know its name!
Waterworld is excellent and I declare this discussion over, unless anyone wants to tell me how right I am. Which I am!