Difficult to imagine how this game is played outside of touch interfaces.
The graphics on the iPad version are much preferred as the iPad's touch screen real estate works much better. Its difficult to imagine how this game would be played otherwise.
Osmos has great music and this shouldn't be under-appreciated. A significant portion of the immersive game experience is the very mellow ambient soundtrack which probably has merit in its own right in that the soundtrack could be used for concentrating, relaxing or even meditating.
There are some real game play mechanics, and puzzle gems in this game. Not every stage can be solved without some thought. It requires foresight into inertia and other physics. The fact that when you propel yourself to create motion you also create a projectile which can cause motion in other bodies can lead to some clever brain teasing puzzle. Sometimes the solution lies in moving yourself, other times in moving others, and sometimes in a timed balanced combination of the two.
Summary: Osmos should be enjoyed for its music, its fluid game play, it's clever challenges, and its minimalistic "less is more" sensibility.