My 6-month-old loves this set, and mom and dad find it awfully cute too!

The set has a sproingy caterpillar with knobbies on his back where the ladybug and the bee can ride. The caterpillar and bee rattle and are fun to shake (and bang together). They are an easy shape to grab and hang on to with little hands. The caterpillar has wheels and can roll across the floor. It's easy to pick up, with a variety of hand grips (including molded antennae).

All-in-all, it's one of the more well designed Primo sets that provides a lot of playability, as well as compatibility with other Primo blocks.