This post is talking about iOS apps, but I'm sure most of it applies to Android as well...
Having a crash report framework for your app is not really optional.
While investing in the QA phase before submitting your app can find and eliminate a lot of the crashes, there will always be something you'll miss, and there's nothing like millions of potential users to help you find and fix these annoying crashes when they happen.
The framework is really simple to use and the documentation is very succinct, so I'm not going to elaborate too much about the basic integration and features (such as symbolicated stack traces for each crash), but I DO want to tell you about some of my favorite features in the framework, that got us at JoyTunes to choose and use it for our iOS apps.