I downloaded (my first electronic book! Possibly my last!) Cleaning Mona Lisa and had a look.
Here's what I like about it: the amazing high-resolution images, the interview with the conservator at the National Gallery of Art, its thesis that understanding the strengths and weaknesses of a certain medium helps us understand and appreciate works of art.
What I don't like so much: the author's "I'm so excited about art and you probably don't know much about it!!!" tone, the surprisingly short length (22 pages), the inevitable but disheartening conclusion that "digital cleaning" will give us electronic copies of paintings that are better than the originals because we can see what they (probably) looked like when first painted. I especially hate the interactive feature where you rub your finger on the painting to take it from its "before" state to its "after." Is that really what iPads are good for?
So, should you spend the few bucks to get this yourself? Yeah, go for it. But be warned: it begins with an annoyingly enthusiastic video, so you'll want to turn the volume down before opening the book. Unless you like annoyingly enthusiastic, but I'm guessing that if you read Art History Links, you probably don't.