They're pretty darned cool. They don't really fly out of ground effect. You just skim along a few feet above the ground or water.
Back in the '90s I dreamed of having one with retractable landing gear, which I could fly over a highway or the water (or... over relatively even ground too). There's a limited 'zoom' capability, where you can momentarily trade speed for altitude to clear obstacles... or that granny blocking the road...
It hasn't really gone far yet, but there is a smallish, not so active community for them. Lots of broken links and the like.
From what I understand they're very efficient, and you can move a lot of weight across the pond, using less fuel than true aircraft (for the payload)
and lots faster than ships.
I'd love to see more of the technology.