To choose the inbox you want to check, simply tap one of your accounts on the left-hand menu. Also, it comes with a Material Design interface makeover (there's a lot more red now) and a thread email system similar to what you get through Inbox.
We can't say which Android flavors it's compatible with exactly, but we've installed it on an Ice Cream Sandwich tablet, so it'll likely work with all newer platforms. To find out for yourself, or to take a break from Google's busy Inbox app, head over to Android Police to download the file.
