When My business was active, suppliers could count on hearing from me when things didn't go well. I sometimes got "thank you"s for that. If things are not good, you should tell the people.
But I also try to be fair and write as many "thank you"s for the times things got done right or even better.
There are problems with any volunteer reviews. So, I read as many as I can before making up my mind. I have run into 5-stars that were obviously written by someone with an interest in the property. I have also read one stars that as obviously had a grudge that they wanted to push. When I run into one of those, I also look at the date if it is old, I may go look. This last excursion was only three weeks and 3500 miles, but we still managed six "look at" stops during lunch or break times.
Yes, I have written a bunch of both for RV Park Reviews and Trip Adviser. As well as our own group and FMCA. As I no longer have a break-neck schedule to keep, it is an enjoyable thing.
Matt