While you read
Kindle's in-book experience is as straightforward as it gets. To turn the page, simply swipe or tap somewhere in the margin. A tap to the center of the page brings up a status bar with location information and reader controls. There's also a menu at the top of your screen, in case you want to change text size, brightness, margins, line spacing, or background color. For now, the Kindle app offers only black, white, and sepia (my favorite) background options, but hopefully Amazon will add other textures and colors in the future.
Long-pressing a word while reading brings up a dictionary definition and a few options, including highlight, note, and search Wikipedia. These added functions really serve to enhance the reading experience, as you can seek out extra information without exiting your book.
As with Kindle on other platforms, Amazon's Whispersync technology makes it so the app can remember where you left off and where you placed your bookmarks, which is convenient. However, it would be nice if we could name bookmarks, rather than try to remember each assigned location.
Send to Kindle
Finally, the Kindle app for Android supports the Send to Kindle feature, which allows you to send files to your account in the cloud and access them from your Android device. Supported file types include JPG, DOC, RTF, and PDF.
Often overlooked is Kindle's Instapaper-like "read later" feature. Using a bookmarklet or browser extension on your desktop, you can actually save articles from the Web and use the Send to Kindle function to read them from your mobile device. While this feature might not be the best way to keep a long list of articles you like, it is great for staying on top of ones that you plan to read very soon.
If you're looking for fancy visuals like 3D page-turning, then look elsewhere. Otherwise, Kindle for Android is a perfectly capable e-reader app that has several noteworthy features. Plus, it's the no-brainer choice for those already committed to the Amazon ecosystem.