I've always found paid reviews to be scummy, whether its the entire hollywood industry, where rotten tomatoes reviews are in the 90% and audience score is like 30%, or on Amazon where it's very very clear that someone paid for reviews. I don't mind when authors incentivize readers to review though. Maybe a dollar off their next purchase of one of your books? Something like that. Many of the paid review sites don't actually read, they skim, and they give a decently high review, because that's what is expected of them.
Just my 2 cents. Play the game as you see fit though. I do understand industry pressure, but you should really think about what is implied by paying for reviews vs incentivizing people who already read the book to review it, and decide if that is something you want for your story or not.