It's really important to properly define those features, otherwise your application may get a lot of bad ratings of incompatibility issues.
For example, if you are developing a live wallpaper, you should add this line in your manifest before the application section:
Unfortunately, this directive does not work correctly on all phones. I have noticed that some devices will not see your Live Wallpaper, although they support this functionnality.
So be really careful, when you define your list of features, otherwise your application may not be visible by a lot of devices.