The jam was good, but the rating system left me cold. I have a total of three issues with it; let's see if you can spot them.
It is obvious right? Ok, I'll give you the first one for free: there are no descriptive words to go with the numbers. Let's fix that.
10 The best ever
6 Above average
5 Below average
1 The worst ever
Better. Now everyone has similar expectations of each grade, more so than before. Do keep in mind this is just an example, there are other fitting descriptions and they could even change based on each category.
Second problem? There is no average! In a big jam there are a whole lot of average entries, so-so stuff. With this rating system I'll have to score them slightly better or slightly worse every time. How annoying.
The last problem is more personal than the prior two. In my opinion a scale of 10 has too much granularity. What is the difference between Amazing and Great? How about Terrible and Abysmal? It is not clear and as such we can expect different people to use these grades in fuzzy ways, which muddles the results. In the best case scenario the grade should reflect the (hopefully written) opinions of each reviewer exactly, not close enough.
In light of the prior explanations some propositions are in order. The first one is obvious, simply introduce descriptive words and an average grade to the current system. I'd be fine with that. Next, two more ideas.
7-grade, zero centered model
+1 Above average
-1 Below average
The old 5-grade model
I rate the rating system 2 out of 5, bad.