Come in small packages?

DON'T let size or age fool you. When it comes to Lil' Bow Wow, good things come in small packages. (What does this sentence mean?)
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The American boy is only 16. But his CDs have sold more than a million copies, with his third record, "Unleashed", released in late August.

The cool thing about Bow Wow is that he is one of the few rappers who don't sing songs that are filled with dirty words. He's got a serious attitude, towards education as well as to rapping.

"Good things come in small packages" is a traditional saying that's used to praise a physically small person. The performer being described is young and (probably) below average height.