If you use the Kindle device itself to shop in the Kindle store, you can browse and search for books, and view reviews, but: the reviews are sorted by time, ascending chronologically. There’s no way I can find to change this and it’s painful to scroll through more than a few (they’re presented 3 per screen, and there’s no way to jump around in the list), so in practice you only ever end up looking at the first few reviews in the list, which means the first few reviews posted.
There are some really egregious examples of this. For Dune, the reviews start in 1996, and even with a lot of clicking and waiting, my patience was exhausted before I got out of 1996. For the Lonely Planet guidebook to Chile, the first reviews you see castigate the 1999 edition, but here in 2010, with the book having been revised several times since then, who knows how reflective that is of the current edition. (Note that if you follow the Dune link on the web, here, you get the real Amazon storefront which shows reviews sorted by “most helpful”, very unlike the Kindle result. That is, I can’t demonstrate the problem I’m talking about by linking to Amazon’s website, because the website doesn’t have this problem. Moreover, the Amazon website doesn’t even show the same search result for the Lonely Planet Chile guidebook I bought, so I can’t link to that at all.)
(Aside: my two examples are also additional examples of times when combining reviews for multiple editions of a product is not helpful. The current edition of Dune, and the one I bought, is the “40th anniversary edition” printed in 2005, so reviews from 1996 have only partial applicability to this edition. And the guidebook problem is obvious, since new editions aren’t just reprints with typo fixes, they’re ostensibly redone entirely.)
It would be better if they sorted reverse-chronologically, or sorted most- helpful-first, or even random if they don’t want the-rich-get-richer — which is a pretty bad problem with the current order. But the current order is pretty much the worst possible one.