As I have mentioned, I am learning Haskell to fill a gap in my programming language tool kit: a concise, productive language with great run time performance (low memory use and efficient utilization of multi-core CPUs).
I am experiencing another benefit: a different way to analyze and solve problems. Learning Haskell reminds me of using Prolog. Obviously Prolog and Haskell are very different programming languages so the comparison is really in how different they are from the languages that I usually use in my work (Java, Lisp, and Ruby). It has been over two years since I used Prolog in a consulting job but I used to use Prolog a fair amount. For the near future I am happy learning Haskell for a few specific applications and for giving me a fresh programming perspective. I am also pleased to see the wide range of Haskell libraries and the Haskell community seems interesting. I have been using Planet Haskell as a launch point for reading.