I ran a free giveaway (it was books and a 50 dollar amazon gift card to try and entice more people) through rafflecopter with sorta the same idea as you, only reviews weren't the only way to enter. They could earn one point by liking my fb page, 1 point for tweeting, 3 for adding the book to goodreads and 10 for writing a review of one of the 2 short stories out (and the short stories were both free when it started). I only had one person enter via the review option and they didn't even really write a review so sorry i've got no help for you, but wish I did
If you add other options to enter i'm sure you'll get more entrants, just not more reviews like you were hoping for. I had a bunch of people enter via the other methods.
If you add other options to enter i'm sure you'll get more entrants, just not more reviews like you were hoping for. I had a bunch of people enter via the other methods.