Oh yeah. What I don't like is the ease with which whatever it is actually manages to do the snatch. I mean, symbiosis is hard to cook up in a short span of time. The stuff needs to be real smart to pull it off. Yes somehow the bosdy-snatching aliens can interface perfectly with our brains soon after apparent first contact.

Reminds me, Greg Egan's Teranesia is a kind of hard-SF body/genome-snatcher involving, well, nothing from space.