When I write my reviews, the most important points are practicality and relevance of information. I consider what I would like to read about a particular place - what information I would like to get - and try to provide such information.
For example - a supermarket. I would like to know if it is easy to drive to, what the parking situation is (how big is the parking zone, is it free etc.), how many people come there and if there are any other shops or services in the vicinity. I consider a review which answers these questions a good review. And this is exactly the kind of information I try to provide in my reviews, to inform people as I would like to be informed.
What I understand by relevance of information is that information about a particular place should refer only to this particular place (when it comes to chains), not the whole company. When writing a review, I always push any grievances I might have with a particular company aside, so as not to let this skew my image of a given place.
I understand that some other aspects or criteria might be sometimes more relevant, but for me these two - practicality and relevance of information - are the most important.