Cooking Mama 3: Shop and Chop doesn't transcend the previous releases. The shopping mode is cool in that it's nice to have something new, but there's not enough content in that addition to make this a must-have title. If you've played the two prior Cooking Mama titles until you could play them blindfolded, then by all means, pick up Cooking Mama 3. You'll probably love it.
However, if you've grown bored of those two titles due to frustration or lack of interest, Cooking Mama 3 isn't going to reignite the interest. It's a fun, quirky little game, but it's the same fun and quirky little game we've been playing for a while now.