Rihanna's Digipak's tend to feature her in a seductive pose of some description. because this plays to the style of songs which she makes, which hinge around the idea of romantic and sexual lyrics.
In this image Rihanna is wearing a revealing top in fitting with her lyrics and song styles, the pose on the left has her leaning back against a wall with one leg raised.
The right image has Rihanna to one side which s more interesting than if she was flat in the middle. The use of warm colours on either side works well for the overall effect of the digipak.
The digipak has an image on either side and a CD in the middle. This 3 leaf cover means she has more room to ad advertising for her other albums (the left side).