One of my favorite books. I won't mention any spoilers, but there is a twist near the end, especially if you are a fan of Verne's other works.
There have been 1 or 2 movies made of this book, but neither really as good as the book.
I hope you enjoy it as much as I did.
p.s.
Side note: if you are looking for other older classic free books, try
Project Gutenberg:
http://www.gutenberg.org/or
wikisource:
http://en.wikisource.org/wiki/Main_Page(this one is a bit cumbersome to use, but it works)
and to translate various e-book formats into other formats for your reader, try:
http://www.convertfiles.com/convert/ebook/EPUB-to-MOBI.htmlNo association with any of the above, just would rather read the classics for free.