We've really just started exploring Boot, but given how much better it deals with ClojureScript (especially in the context of http://cljsjs.github.io), we're taking it rather seriously. For my personal side-projects, I've just started a new one with Boot. My experience so far is that it's definitely not as "full-featured" an experience as Lein, but it does feel more "composable" and, dare I say it, more "like Clojure".