The comment is undeniably harsh, and could not be construed as constructive criticism even if I squint very hard, but it is also not a flame. There is not a personal attack on you, the author, which is what constitutes a flame.
While we can always hope that all users here will conduct themselves like adults, given that this is an adults-only venue, there will always be those people who will leave reviews that are no more than a bluntly expressed opinion. As the author, you always have the option to remove the review if you choose.