People saying "who cares" but it does matter. Widely acclaim albums have a chance to sell more. If people were skeptical about buying the album and see a good review, they're likely to see what the fuss is about.
They're more likely to download the album and check to see if they like it themselves. Leaks have taken the meaning of reviews away completely. These things don't matter anymore. Either they get the download or they will ask their friends what they think and if they're friends like it, they'll check it out.