I think it is both old-time Lisp'ers and JVM platform programmers looking for something more agile than Java.
I have been using Clojure for my work for several months and for me some of the big wins are:
1. easy to use existing Java libraries
2. lots of nice language features like destructuring, etc.
3. nice integration with Java and/or Scala projects with IntelliJ
4. fairly good runtime performance
And, a few hassles:
1. error stack traces have relatively little value.
2. The Clojure team is doing great work, but I still feel that the platform is not quite there yet compared with Java, Common Lisp, Haskell, etc.
I am in a patient mood in regards to Clojure: I use it for some things now, and expect my percentage use of Clojure over other languages will steadily increase over the next few years.
I use Clojure for a few odds and ends on a fairly regular basis now, but not having a Java background was a definite hurdle for me when I was starting to learn it. It was sometimes tough to tell if the problems I was having were Clojure related or Java related. The entire CLASSPATH paradigm was an issue for me until I realized what was going on.
For my current work task, I am using it for information extraction from Freebase which requires a lot of JSON manipulation. I was using Ruby but Clojure use is preferred at CompassLabs (both languages are well suited for Freebase data hacking).
I mostly use Java for Hadoop machine learning work, but I may transition to Clojure in the next few weeks (my CTO has suggested this).
Earlier this year, I added Clojure examples to my last book on the Semantic Web.
I have been using Clojure for my work for several months and for me some of the big wins are:
1. easy to use existing Java libraries
2. lots of nice language features like destructuring, etc.
3. nice integration with Java and/or Scala projects with IntelliJ
4. fairly good runtime performance
And, a few hassles:
1. error stack traces have relatively little value.
2. The Clojure team is doing great work, but I still feel that the platform is not quite there yet compared with Java, Common Lisp, Haskell, etc.
I am in a patient mood in regards to Clojure: I use it for some things now, and expect my percentage use of Clojure over other languages will steadily increase over the next few years.