I've been using Dash for more than a year now. I love it. It is great for quickly looking up things, and best of all it works for multiple languages. I regularly write code in Clojure, Perl, Java and C, I also use Redis and PostgreSQL, and Dash helps with all of that.
My only wish is that someday I could get Intel's x86 manuals and ARM Cortex M0 and M4 instruction set documentation in Dash.