At first glance, Shuffle doesn't seem to have much depth. In many ways it doesn't, but there is some strategy beyond "roll the marble as hard as you can and knock stuff around". Rebounding physics play a large part in the game and can help you take out several yellows with one throw. Try banking a shot off the corner of a marble to see what I mean. And learning to tweak the strength of your throw is a key skill, otherwise you'll overshoot and lose a marble each time you take a shot.
As the game progresses marble arrangements shift and stack the odds in the computer's favor. The difficulty doesn't increase much, however, and the skills you pick up early on should be enough to keep you in the game.
Analysis: Shuffle is well-designed with easy controls and attractive visuals. No flaws in the presentation, but the game itself leaves a little to be desired. Your attention will only be held for a few games before you crave something with more depth. This could have been remedied with new marble layouts, more difficult stages, obstacles, or even a new game mode or two. Instead, Shuffle relies on one basic concept and stretches an entire game around it. It works like a charm, but only in short bursts.
Shuffle is a great game to fire up for a few rounds when you're itching for instant gratification.
Cheers to Mark and Zeroster for the link. =)