To be honest, there's nothing wrong with positive and negative reviews of CDs, it isn't that hard to look at them and try to judge which reviewer would hold a similar opinion to your own, and go from that as a point of reference. The Negative reviews are there for a reason, because not everybody thinks that Radiohead is the best band in the world, and not everybody listens to / likes Alternative Rock (or Progressive Rock). The things you find appealing about their music the next person might find repelling. There are people out there that like Radiohead simply because they are popular and people out there that dislike Radiohead simply because they are popular.
edit: And the reason there are so many reviews and so much differentiation between opinions is because of exposure, because Radiohead is a rather mainstream artist, the majority of the world population is exposed to mainstream music, You will probably find that if you went onto rateyourmusic.com and looked at the ratings that people gave that particular radiohead CD, most likely the people that gave the CD less than 3 stars would have a rather different taste in music to yourself.
Whereas with lesser known, underground and more "avantegarde" bands, there will probably be alot more positive reviews towards their work because the only people that are going to review them are the ones that went looking for their music, because the majority of people wouldnt even know about their existance in order to be able to write a review saying "too out there", "doesnt make sense" etc.