I'd love to read a chapter about why would someone choose Common Lisp instead of, say, Clojure (with all the JVM ecosystem behind it) or LFE (with the Erlang ecosystem behind it). What are the use cases in which CLISP stands out and offers a benefit?
Disclaimer: Amateur's blundering travelog. I've been dabbling in Clojure for about 4 years now, off and on, and it works very well for small-ish projects. The integration, as others have mentioned, with the JVM is superbly seamless (it leaves Scala in the dust in this respect) and this opens up most of the Java ecosystem. Also, the STM model of concurrency management is super cool. So far so great! But every time I t…
It is definitely highly mature, rock solid and the choice of most professional Lispers. It anticipates many problems one doesn't even know one will have, and solves them.
In the negative column, it's a bit crufty for historical reasons (e.g. (aref ARRAY 1 2) vice (gethash KEY HASH-TABLE)) and made some choices which in retrospect were foolish (upcasing symbols being a huge one). The former doesn't really matter, and the latter can be solved with a simple (setf print-case :downcase).
For a long time, there were few good resources for learning Lisp. Fortunately, that's changed. Peter Seibel's Practical Common Lisp (http://www.gigamonkeys.com/book/) is a must-read: it explains a little of why Lisp is so relevant for modern development. Edi Weitz's new book Common Lisp Recipes (http://weitz.de/cl-recipes/) is worth its weight in gold.
Quicklisp (https://www.quicklisp.org/beta/) is a great place to find a lot of great packages.