Can you still review an app you "purchased" with a promo code?
Seems like a flaw to allow people who didn't pay for the app to rate it. This would also allow giving away codes in exchange for a certain amount of stars.
It wouldn't be surprising if these reviews were fully paid. The developers get most of those payments back, so the expense of buying your own app a couple hundred times is insignificant in comparison with the income generated by being highly rated.
As far as I know, no, you can not longer write reviews from apps downloaded with promo codes. It seems that the change was recent (couple of months ago). A google search showed lots of articles about but I couldn't find an official Apple statement about it.
You still can. I've had friends review my apps even though I gave them all promo codes. And for the record, I don't think it's unethical to ask a few friends for a favor.
It'd actually recommend as a marketing strategy to hand out as many promo codes as possible. To bloggers, friends, anybody who asks or complains about your app on twitter. The goodwill you gain is worth far more than the potential lost sales. Even at $20, I think giving out promo codes has made me much more in good business than the thousand bucks in "lost sales."
Seems like a flaw to allow people who didn't pay for the app to rate it. This would also allow giving away codes in exchange for a certain amount of stars.