I like some hard SF. I think one of my biggest problems with Red Mars was that it is too much outright science, not enough story-telling. I didn't find any of the characters interesting. Believable, yeah, but none of them made me feel empathetic, which is a huge draw for me. Also, the hard SF I like is usually theoretical astrophysics. This book had physics, chemistry, biology, environmental issues and engineering involving all three areas of science... just couldn't hold my interest, I suppose. To each his own though.