There is one million ton of heavy oil, light-water nuke reactor, massive food aid to follow. After all things are said and done, the difference of offered aid money between the two would narrow considerably.
Sounds like a good strategy to separate NoKo from their [few remaining] apologists. This is a bait to show our "good face efforts" to the rest of the multi-party participants that we've gone the extra mile to enforce the terms of agreement.
If NoKo refuses to start allowing inspections and disarmament, there is no more excuses or phony accusations they can offer, it's over for them, and screws will be seriously tightened, next "agreement" will not be so "generous" for them. China is already cheesed off on Kim, if he starts causing problems after this "gesture of good will" he'll be in a heap of trouble with Chinese. They stand to lose the most, if their "client" doesn't play by the rules they helped set up.
$25 million "advance" of their own "frozen" assets is cheap and shrewd way to flush out Kim's intentions.
Good thinking by Condi, she is probably a good chess or poker player, 5 moves ahead of boneheads in State Dept.