I find them generally informative, it depends on the book I guess. If something has 20+ reviews you can easily get a pretty good feel for it. I'd agree with you

I find them generally informative, it depends on the book I guess. If something has 20+ reviews you can easily get a pretty good feel for it. I'd agree with you on obscure stuff with only a handful of reviews. As long as you don't have to trust any single reviewer there is a lot of good information to be had, same with IMDB really, every popular movie has reviews at each extreme, but given enough choice in reviews you can get a decent feel for it.