It is unusual for an incoming administration to actively pursue and aggressively prosecute the misdeeds of an outgoing administration. Gerald Ford pardoned Richard Nixon rather than go after him. Liberals howled about that, and Ford lost re-election.
But Nixon's crimes were so paltry compared to Bush's. They were also far less numerous. In fact, I sort of feel sorry for Nixon (and Bill Clinton too) for all the heat they took over relatively bupkis charges.
For his part, Barack Obama is playing the gentleman, not wishing to appear to be going on a witch hunt. But since when is forgiving torture gentlemanly? How about warrantless wiretaps? Spying on ordinary Americans--apparently all Americans? Jonathan Turley doesn't think so, and he has a much bigger brain than I do, so take a look.