My experience with Kirkus: I paid for a review of one of my novels and found that a) the reviewer wrote a summary of the book, which anybody could have seen from the blurb; b) after that, I was bombarded with e-mails asking me if I wanted to pay for their such-and-such promo plan. I told them I had a publisher, and no, thank you, but I kept getting these e-mails until I was quite short with them. I think it was because they assumed I was self-published. Anyway, I didnt like that.
HOWEVER, the one paragraph of the review which was actually a 'review' and not a summary of the story, was very positive (not a 'star' review, though), and it's been used by my publisher in marketing the book. Also, somebody in the industry saw it, was looking for that particular kind of novel, read the book, liked it, and it was subsequently picked up for Audio. The Kirkus comments about my writing and characters, story etc, are on the back of the audio book so they obviously thought it was a good thing to have. So, for me, looking at the advance I received and the royalty statements, I think it was money well spent. Would I do it again? Yes, if I had a book I thought could fly a little longer/higher I might take that chance and fork out. HTH.