Lisp has a lot of things to teach us, and it's a very practical tool in its own right. It has all the features you're used to in other languages, usually done very well. There are plenty of good reasons to look seriously at Lisp, and Practical Common Lisp is the best introductory Lisp book out there.
The things that most people don't see when they study Lisp are the interactive development style, macros, and practical applications. Peter Seibel gets you started off properly right from the start, walking you through picking a high-quality Lisp implementation and IDE, and then teaching you how to use it. This is one of the biggest things about Lisp: your program is running as you write it. You write and debug programs incrementally, and it feels good. After getting you started on the basics of using Lisp, Seibel plunges right into writing a simple CD database, with fast compiled queries that look almost like SQL in Lisp.
After you learn more of the basics, Practical Common Lisp goes into the next big neglected topic in Lisp: macros. Ever practical, Seibel uses macros as part of a very pleasant unit testing framework that only takes up 26 lines of code, all of it easy to understand. Macros are a powerful tool, but easy to abuse. This book doesn't abuse them, and that rubs off on you.
The next few chapters cover, clearly and completely, topics dear to the heart of every programmer: high-level data structures, file I/O, object-oriented programming, string processing, complex looping constructs, exceptionally powerful exception handling, and more. I use this book as a friendly reference; whenever I forget how to use something, I look it up here.
From then on, the book is all practical examples. A spam filter, an object-oriented binary file parsing framework, an application of that binary file parsing framework to get ID3 information from MP3 files, and a lot of web programming.
Practical Common Lisp is already the book universally recommended by the Lisp community for learning Lisp the right way. Read it, and you'll never program the same way again.