"A generic extender making physically impossible claims for a price that's still too high."
The '15,000 sq. ft. coverage' is a marketing fabrication. This is a simple signal repeater that might push a weak signal into an adjacent room, covering perhaps 500-700 sq. ft under ideal, open-air conditions, with significant speed loss.
This device might be considered only by someone who needs to get a 2.4GHz signal to a single, static, low-bandwidth device like a smart plug in the next room, and who cannot find a reputable brand's entry-level model for less.
Anyone needing reliable throughput for streaming, gaming, or video calls should avoid this. Users seeking true mesh networking must buy a system from a known brand, as this device's 'mesh' mode is not standards-compliant. The lack of security updates makes it a poor choice for any security-conscious user.