I have one, it's convenient and lets me control my home in what feels like a natural way. Personally, I don't see the downside of having it.

Note; I mean I don't acknowledge a downside from my perspective. I'm fully aware that it's always listening and sending data home when it hears a keyword. According to Google, it will only send voice data back when it hears the keyword. Now if it explicitly goes against its own stated privacy policy, that's a breach of trust I would not be happy with. That said, if they explicitly stated they send all audio back, I'd actually be fine with that too.