Compared to much of the anime that I consume regularly, Usagi Drop is a very sedated show in both action and drama. Yet there is a constant level of emotional appeal that makes every episode so enjoyable. It rests in how honest the characters are, especially Daikichi. He does not lie to himself about the situation he has set himself in, what he gives up in life by taking in a six year old. He recognizes the difficulties of child rearing, and learns from figures in his life the potential struggles it causes.
Rin, but you never fault the show for this idealization as Daikichi's own great efforts at making this family structure work garners sympathy and respect.