Seconded. I was working with a mix of Java and Ruby for roughly a decade. I've been working full time with Clojure for about two years now, and on and off for a couple of years before that.

Fantastic introductory guide. Clojure really needs something like this. There are some good books on Clojure but I find they are aimed at either the determined beginner or the experienced (or both.) This though I feel I could pass around to anyone that wants to get an idea of what Clojure is about.