At 300 miles per hour top speed, I think you’ll just hear the jet engines and then either see a gray blur or die.
Unless you happen to be behind a decent sized hill, then you’ll just go deaf and wonder what the fuck that noise was. A 5 meter service ceiling is impressively low for a craft that is 19 meters tall.
It was probably developed to push the limits of ground effect, since it can provide such a great advantage to travel efficiency. Think min-maxing to find the meta in a new competitive game.
Would be interesting to see how that thing would fare in a modern war. On the one hand, it can deliver a shit ton of missiles very quickly. On the other hand it has a radar echo like, well, nothing like it I guess, and it certainly flies slower than any missile.
I would guess that it would survive about as long as it would take a $200 fpv drone to collide with one of the engine arrays. Then nautical drones would do their thing to turn it into an artificial reef.