One probably doesn’t need to reread this to read Before Mars, but I felt like doing so anyway. I couldn’t quite remember all the details, and I remembered enjoying it, so hey, why not? It’s definitely as good on a second time; maybe more so, because certain things take on a different significance. You know about the rather metaphysical flavour of the ending, you know what the mysteries are and where the mines are in the field, so you find yourself wincing for the characters and wishing they’d watch their step (and watch out for who to trust).
It’s still a bit intense reading about Ren’s anxiety problems, but I have more distance from it myself now, which made it less uncomfortable and more just… it’s interesting to read, interesting to see someone handle mental illness in a sci-fi setting in this way.
It’s well worth the read and the reread, and I really must hurry up and make my wife read it.