Not only was I asked twice (before and after my safari) to review Africa Veterans positively, but I was then e-mailed to ask me again to review them.
Tripadvisor, I believe, is a community for travellers to use as and when they see fit, not for tour operators to use as a marketing tool. I am happy if Africa Veterans have done well from positive reviews, and I myself, was perfectly satisfied with my tour with them. This harrassment to review them (in their words so that they can be number 1) is, in my opinion, contrary to the objective of Tripadvisor.
Admittedly they have not offered bribes or discounts for reviews, but that doesn't make such begging letters any more pleasant. A sour taste to end a perfectly pleasant trip.