A phrase commonly uttered by noder
alex.tan - because he was. But that's an aside.
This phrase reflects the awe and satisfaction in one's self when a task is accomplished as well as it was. The individual may be pleasantly surprised at how well the task has turned out, and it reinforces self-confidence. Basically, we should be able to say this more often.
It fulfills the Ego/Esteem in Maslow's hierarchy of needs.
When uttered aloud, makes those around you think "Damn, he's good!".