My Sams Teach Yourself Regular Expressions in 10 Minutes has proven to be a very popular book, and tens of thousands of developers have used it to get started with Regular Expressions. The book teaches RegEx incrementally, and for each example a block of text is used, and matching text is shaded to clearly demonstrate what the Regular Expression is doing.
Sams Teach Yourself Regular Expressions in 10 Minutes has apparently now been released for the Amazon Kindle. I've not seen the Kindle version yet (as I don't have a Kindle yet), but readers are reporting to me that the Kindle version is missing the shading, making all of the examples rather useless!
I've contacted the publisher about this problem, and hope they'll correct it quickly. But for now, I suggest you avoid the Kindle version of the book, and stick with the print version.