It's not personal; I think he has an agenda other than faithfully upholding the laws and Constitution of the state.
He's really into upholding his own authority and that of his branch of government, with a penchant for instituting cases against politicians he doesn't like. A DUer recently said that every branch of government should seek to expand its power to the limits allowed by law: Chaudhry would whole-heartedly support this, since his branch says what the law actually is.
He has a lot of support from the lawyers (or jurists). Mostly because the legal system is a way of leveraging power. Generals control state-run companies, and their decisions have an impact far beyond their modest means or accomplishments. Jurists get to make a decision to impose, crudely speaking, their will on hundreds or thousands of people. It's one of the power centers, and the Pak way is for power centers to first look out for themselves and their own.
Chaudhry also has an odd habit of deciding ambiguous laws in a rather unambiguous direction: If there's doubt, the more conservative you are--including Islamist--the more likely you are to win. There's a tendency to say he's just enforcing civil or human rights, but the lopsidedness of the application suits a lot of Islamists just fine. It's an odd mix, since the jurists are probably the most liberal section of society.
(Then again, they're united in wanting to overthrow the established order.)