Anyone considering this should scroll down to the bottom of the indiegogo page and take a good look at the "Video" chart. Based on that, it seems not to do any upscaling of interlaced video modes, which includes everything output by true retro consoles.
It also doesn't seem to do any framerate conversion, which they seem to imply by touting 120 Hz. Well, according to their chart, the only way you get 120 Hz out is by putting 120 Hz in. All of the other modes seem to match input & output frame rates, as well.
It's not hard to imagine they're doing something like Radeon Image Sharpening. Perhaps with some median filtering, in "retro" mode. I'm mainly disappointed they don't include deinterlacing, as that would most benefit true retro consoles. I also think that suggests they're not doing anything terribly fancy, like employing true super-resolution techniques.
Their promotional video also mentions something about color enhancement. I'd probably turn that off, if I could.