The Canon Vixia RF800, in a nutshell, is a $300 camcorder that can do (at least) one thing your smartphone can't: zoom.
The RF800 offers a 32x optical zoom lens, combined with digital zoom for a 57x hybrid zoom. That's paired with a 3.82 megapixel sensor that's been the same for the past few generations of the line-up.
Compared to the older R700, the camera now has slow motion modes, as well as backlight compensation to help shoot in auto mode under crappy lighting.
For $300, the R800 is a basic camcorder -- there's no wi-fi and no built-in storage, unlike the R82 and R80. But, if you're looking for a cheap camera with a good zoom, the R800 isn't a bad option. If zoom's what you're after though, the Panasonic V380 has 62x of it, along with wi-fi for the same price point.