The official Google Calendar app for Android is free to download on Google Play and offers a reliable and intuitive experience. The app lets you see events up to a year in the past, add calendars from multiple Google accounts, create new events, and more. It even comes with a nifty Home screen widget that shows a snapshot of your agenda.
If you use Google Calendar on the desktop, then the mobile app's interface should feel familiar. It offers similar viewing options, including Day, Week, Month, and Agenda, that are all accessible via the drop-down picker on the top left of the screen.
While I generally use the Month view on the desktop, I find it less usable on my mobile device. It's a lot of information crammed onto a smaller screen, and the colored bars marking events can be difficult to decipher, especially when you have several events falling on a single day. That said, I have seen other calendar apps able to use the real estate more efficiently to display at least some text, so it's a wonder why Google can't figure it out as well. As it is now, the Month view is good for getting only a quick top-level glance at a large chunk of time. To move between months, you simply swipe up or down, and you can even see portions of two consecutive months on the same screen, which can be helpful when scheduling events at the very end or beginning of a month.
The Day and Week views are both broken down by hour, giving you a lot more room to see the details of your schedule. You can also use the pinch gesture to zoom in and out, in case you need to see more details all on a single screen. Meanwhile, the Agenda view shows only scheduled events, color coded, all in list form.