How do you get consumers excited about yet another expensive high-end smartphone, in a U.S. market that seems to be maturing? Maybe the answer is to simplify the thing, and stress just a few interesting new features, like the ability to survive being submerged in water, or to act as a heart-rate monitor.

That's the strategy that Samsung, the global smartphone leader, hopes will work for its latest top-of-the-line model, the Android-based Galaxy S5, which goes on sale in the U.S. on Friday at all major carriers.