Just a heads up, don't go in to Echopraxia expecting it to feel like Blindsight. When I first read it, I was actually pretty disappointed overall, and a few of my friends had similar reactions.

Over a couple of years a few re-reads, though, I've come to enjoy it perhaps even more that Blindsight, but in a completely different way. It fills out a lot of the posits opened in the first novel, without coming to specific conclusions, but it gives you a lot to think about.