I agree...app crashes every 15 minutes is way too excessive. You may have the occasional app crash but not every 15 minutes. But perhaps he's using buggy apps. I've only used Google Books a little, so I can't say whether or not it's usually buggy/crashy (I usually use the Kindle app).
If an app crashes, definitely submit a crash report. As a developer, I appreciate getting crash reports (which show up in the developer console). It usually shows exactly where the app is crashing and it's pretty easy to find the bugs and fix them.
By the way (in response to Kevin Oates), app crashes are due to bugs in the app, not because of Android itself. If an app crashes, it means it didn't properly handle an error condition. I think it's more of a challenge on Android (vs. iOS) to have error-free code because of the many different variants of devices, screen sizes / pixel density, OS versions, etc. But that's just the nature of Android. I've found in my own development that in many cases when I troubleshoot an error on a particular device (that works on most other devices), I usually uncover a bigger problem in my code that should have been fixed to begin with. For instance, when I first started learning Android development I didn't understand how to manage bitmaps in memory. I tested on my phone and my app worked perfectly, but on another device with less memory it was crashing like crazy. I then learned how to optimize my app and make it run efficiently even on lower-end devices. It forced me to write better code.