Random House and Zogby did a poll of the reading and book-buying habits of over 8,000 adults. They generated some interesting results -- for example, only 11% of respondents said they are comfortable reading books in non-traditional formats, such as online or with an e-book reader or PDA -- so it's worth taking a look at.
Here's one stat that I found especially interesting: "When asked what makes them want to buy a book, 60% said suggestions from friends and family members, while nearly half (49%) said they are influenced by book reviews." (emphasis mine)
So reviews are definitely still having an impact. If only the people running newspapers and magazines would listen.