She seems like a “stealth justice” pick. That didn’t work out too well for conservatives when Bush nominated Justice Souter. I don’t see any benefit to conservatives if they try to fight her nomination. If Republicans ever manage to win the presidency again, the existence of so many women on the Court will just make it easier to nominate smart conservative men without regard to the demographic makeup of the Court.
I would also say that she’s not really qualified to be a Supreme Court Justice, because she has absolutely no experience working as an appellate judge. I think that judges on the highest Court in the country should get some experience at a lower level court first. But this is still not a valid reason to oppose her nomination, if that's what Obama wants. It only makes her liberal voice weaker against the more experienced conservatives.