As for me, I find reviews supremely useful. I'm not going to stand at the game shop and try to read an entire book, or figure out if the rules make sense (but don't get me wrong, I knew immediately that
Rings of Power, among other d20 books, were not for me). Thus I read reviews. I'd dare to say almost every d20 product I've bought has been precluded by a review (ok, well maybe half

~ I can afford to be a little impulsive).
Psion, I read your reviews
almost to the exclusion of all others (I do read others, if they are reviewing a new product I'm interested in, of course); I also read Monte's, but he only gives one per month.
On the subject of 'grade-inflation' with regard to d20 products, yes, I really think there is some of that. It's almost gotten to the point (for me, anyway) that a product with a 4 is really not worth buying, unless it's something I
really wanted.