It'll be good, but no way it's as awesome as the book. The good news is that I read it back in January, so maybe I'll have forgotten enough that it won't ruin the movie. I remember reading Jurassic Park right before it came out and thinking the movie sucked. Took some time to forget how good that book was to really see that Jurassic Park was a pretty damn good flick.
Also, this flowing water on Mars stuff is pretty awesome. Almost makes up for the thick cloud cover that ruined the eclipse for me.