If you've tested any of our apps on your development machine using the emulator, you already know just how slow this can be. Startup times lasting several minutes aren't uncommon, and then once the emulator is going, performance is absolutely horrible.

There is some hope, in the form of GenyMotion (http://www.genymotion.com). It provides a faster emulation environment, and makes testing much, much easier.

Even so, don't assume that GenyMotion or the Android Emulator always reflect how your app will look and feel on a real device. Even GenyMotion's emulator is rarely as smooth as a physical device. Furthermore, graphical glitches when using Host GPU acceleration aren't uncommon—but thankfully they do not appear on a real device. All of this is why it is so important to test on real devices.

Finally, do not assume that the emulator can provide every feature that a real device can. Both Android and GenyMotion can simulate various features, but not every feature is available. For more information, see http://developer.android.com/tools/devices/emulator.html and http://www.genymotion.com/features/.