I'm a bit torn here since I feel like a good review was part of the expected "payment" to the developer (reading in between the lines suggests he accepted a low

I'm a bit torn here since I feel like a good review was part of the expected "payment" to the developer (reading in between the lines suggests he accepted a lower payment in exchange for a good review). Is it against the site TOS and sketchy? Yes. But then the author is just as responsible as the developer for agreeing to such an arrangement. But it becomes understandable that the developer would withhold the product if he had not yet been "paid" in full.