I've never really had a regular as such, not my way, but a couple of girls I've seen a few times. I noticed I haven't reviewed the girl i've seen the most (bit like NIK) so was going to do a review - but it's a bit difficult.
The trouble with reviewing a regular is that if you say something, anything, out of turn, she will take offence and retaliate by banning you from ever seeing her again.
If you've seen her for a number of years then you will have built up a relationship, even though it's a paid for relationship, that will embody a certain level of trust, and given the vanity and sensitivity of women, she will regard any criticism as a betrayal.
If you have a regular and you want to keep on seeing her, it's best not to say anything.