^Hnn. It really depends on the incarnation that you're talking about.
In most post-Crisis presentations of Captain Marvel (the entirety of Jeff Ordway's run and Geoff Johns' depiction in JSA, basically), Billy Batson does indeed have the wisdom of Solomon when he transforms, but it's still the wisdom of Solomon as interpreted by a child. He could interpret it in childish ways, he could interpret it wrongfully, or he could even ignore it outright if he chose to. He doesn't, for instance, have the personality of Solomon; he's still quite outgoing and optimistic and wide-eyed as a adolescent might be, as evidenced by his frequent usage of "Gee whiz," "Holy moley," and other dated phrases (which is also due to the fact that Fawcett City is generally a pretty dated, old-fashioned city).
But I understand that this was much less the case in pre-Crisis versions of Captain Marvel and some post-Crisis versions. In these cases, Captain Marvel does come across as an adult man with more adult sensabilities.
It all depends on the writer. For instance, Jeff Smith's version of Captain Marvel -- that was seen recently in his Monster Society of Evil series -- however, is an actual, separate personality from Billy Batson. The essence of "Captain Marvel" has existed before Billy ever met the Wizard; Billy is his host and his originator in this era, but the two of them speak of each other as different people and even has memories that the other does not share.
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