High for the 'good categories' is desirable and high for the 'bad' categories isn't. For price, higher is better (for the quality of the blade).
Overall score is exactly that but is calculated by adding the good categories and subtracting the bad ones.
Bear in mind everyone's different - especially the razor you put it in. The blades have been scored after being used to bluntness in either a Merkur 38R or Progress. Progress (fairly recently acquired) is my 'control' razor now for reviewing new-to-me blades.
Price is the most potentially vague of the categories. It will change over time and can vary at any time between different sellers; then there's shipping costs, bulk deals, import and other duties - it's not supposed to be comprehensive, just a rule of thumb based on what I've paid or seen at the time (some blades were PIFs from other members but I still gave them a pricing score). When I started out I looked at price more than I do now so it's for the user to decide how important that is.