Never trust a 5 star review - nothing is that perfect.
I want to know the flaws, the problems, the criticisms - then I know what I have to deal with - whatever the product being sold.
This pulled me up a little the first time I read it, decided to come back and comment - in polite semi-disagreement.
I too want to know the downside of something in a review, but I don't think that 5 stars is an impossible target.
Reason is - used to know someone who amongst other things had the job of overseeing the marking scheme and the marks given for an GCE exam board. He got terribly frustrated that the examiners for art, english and history wouldn't use the full mark range. The lowest they tended to give was 25%, the highest 75%.
He'd say to them "could you expect a better painting from an O level student". "No" "Well give it 100% then!" "Oh we couldn't do that"
So I've got a bit of at "thing" about using the full mark range.
Continuing the thought in particular regarding context of the marks - at the moment I'm reading a military sf. These do tend to follow a formula to a certain extent, and don't often have a "hey that's truly original" moment, but in its classification it is pretty good, well written, interesting aliens, good storytelling, I like the characters and depending on how it ends I'd be varying between 4.5 and 5 on the review at the moment, as I'm enjoying it. Very likely to read the sequel.
But if you were to put it on a scale where to get a 5 it had to be a truly original piece of literature with astounding prose, then it would probably be a 3.
So now I want to add a button that says "great light entertainment" to my desire for a button that says "good but not to my taste".