I love to learn new programming languages. Common Lisp is a great language to learn just to broaden one's horizons.
It may not be particularly cool or popular right now and you may find the syntax ugly but there are so many ideas that really don't come up in other languages. You'll soon appeeciate why the syntax is like it is and why that is so powerful.
Especially if you are from a fairly rigid OO background, the emphasis on a more functional approach and the concepts of treating code as data are fascinating and may offer a new way to look at problems. But Common Lisp isn't truly functional and has a powerful object system too.
You do almost inevitably have to get over using Emacs as an editor but don't let that stop you from just learning and playing. Just the theory is enough to make me think in whole new ways about problems.
There are many resources at different levels but by far the best I've found is Practicle Common Lisp which has the added bonus of being available free online!