I work for one of the big "brand name" companies (I don't want to say which, but it's on the "companies using Clojure page"), and on my team we try and start all new projects to use Clojure.

Frankly, I love it. After the "zen" of lisp clicked for me, Clojure gave me an OS/2-style "Better Java Than Java". Suddenly I was able to compose standard JVM library stuff in a more-natural and easy way than I could in vanilla Java, I was able to easily define relatively-well-optimized persistent data structures, and I could quickly provide new semantics to the language as I saw fit. Also, the Clojure REPL provides an amazing level of increased productivity.

Do I miss the Hindley-Milner type system from my last job? A bit, but surprisingly it doesn't bother me as much as I thought with Clojure.

I don't know if Clojure was just a fad, but I think that it'll always have a loyal fanbase, like mosts Lisps.