When it works, it works (as in, when you're first or second product of the day, you can count on it being a consistent source of traffic for months to come).
Don't be fooled into thinking a couple of hours spent on a Product Hunt launch is real marketing though. You need consistent effort, not a big bang.
I was under the impression that Product Hunt and such sites are good if you want to get eyes in general on your product and maybe increase your popularity within the tech scene but those people might not match the target demographic for customers. Is that wrong? I'm guessing it depends on who your market is.
Don't be fooled into thinking a couple of hours spent on a Product Hunt launch is real marketing though. You need consistent effort, not a big bang.