I like Google's Play Books app even though it's severely crippled due to Apple's policy of prohibiting links to external stores, which doesn't make it very useful if you want to browse and download some new reading material to your device (to shop books, visit Google Play in your browser).
Other than that, it's a solid reading app and perhaps a nice gateway drug to Google's other content stores.
It's been a while since Google last updated Play Books so today saw an interesting update which has brought out three useful features. I've included the description and a few nice screenshots right after the break...