Yeah, I didn't really think about his being younger in the Minions movie (which I haven't seen yet, and I likely won't until it comes out onto blu-ray/DVD). Still, that makes him sound like an entertaining character.

Keep in mind, of course, that Stuart is considered a "teenager" in Minions...so he shows something of a different personality than when he's seen in the (so far) two Despicable Me movies. He's more interested in romance, he's always got his guitar on hand, he's easily distracted (and sometimes caught unawares), and occasionally has a blase attitude about what's going on around him. And he likes to be the center of attention. All of which are fundamental teenaged traits.

Of course, as seen on page 2 of the Characters section of this source, the particular minion pictured here is Phil (who fans will know is not really a baby, but an adult minion in disguise while on a spy mission): http://www.animationsource.org/despicableme/en/chars/Phil/56196.html

All of the minions are awesome in their own way. For me, I personally like Stuart. He's fun yet stuffy (the Minion movie casting shows his more uninterested side).

Baby Minion is best Minion.