In Ha'aretz, Professor Yagil Levy criticizes the Israeli government for hasty decisionmaking, too much deference to the military, and for having both unrealistic and unclear goals. I think he's likely mistaken on a variety of grounds, and I don't know if he even has his facts right (maybe Israel had a contingency plan ready to go in case of another attack by Hezbollah, and the reaction only seemed hasty), but it's food for thought.
I don't want to confuse different issues: just because Israel's actions to wipe out Hezbollah are perfectly legitimate doesn't mean (a) they are wise; or (b) they were well thought out, even if they turn out to be wise. Lord knows Israeli governments have done many things that I think are morally justified (e.g., allow the resettlement of Jews in Hebron, to reestablish an ancient community wiped out in a massacre by local Arabs in 1929), but were exceedingly unwise.
UPDATE: One reason I wonder about the judgment of Israeli leaders in the case is I get the strong sense that the military grossly exaggerated how effective air power would be against Hezbollah. Well before the current battle erupted, I had read the the IDF was begging the government to allow it to "wipe out" Hezbollah fortifications and missle launchers near the border. The implication was that the IDF believed, or at least claimed, this could be done rather quickly and painlessly. In the event, it looks like wiping out Hezbollah's military threat, if it's politically feasible given international pressures, will cost dozens of Israeli civilian and military casualties, and extensive damage to Israeli cities and its economy. This may very well be worth it [I think it is, as, more importantly, from what I've read, do most Israelis], but one would like more confidence that Olmert & Co. were actually cognizant of these costs from the beginning.