And given that a while after that I went through the round (at least 12 interviews by 10 unique people) at AWS because of it (though I later turned that down - I wanted a combination of tech and customer focus, they wanted either one or the other and felt I was too strong technically to be used on a customer focused role)...
Yes.
It works.
If you are hiring you should think hard about how you present it. Corporate-speak is ill-advised, and less is definitely more. Plain developer-to-developer language is the best route.
It is not unusual for candidates to go back over old whoishiring posts, filter by city and then look... so if you can include a permalink to a "positions available" page on your site you will continue to reap the rewards of a good, short advert for quite a while. Make sure to include an email address too (in the advert) so that HN candidates reach you directly rather than get lost in the official HR process.
If you are going for a position, I would advise that you use the opportunity to strike up a conversation and learn about the position and company, rather than just spam them with your CV (how does that help either of you?).
And as mentioned above... look at the whoishiring posts for the last quarter or 6 months, a company in growth probably is still looking.
It works, so long as you realise that this platform connects individuals, rather than treating it as an agency/corp HR style thing.