Saddam was a threat, yes, but not nearly as much as Iran.
the big problem with Iran is that unlike Iraq (under Saddam), Iran has a truly deep hatred of Israel (and the US). Saddam has had anti-Israel rhetoric and has even fired on them a few times, but it is always because he wants to stir up Arab support, not because he could really care less about Israel one way or the other. the only real problem he had the US was that we wouldn't let him overtake Kuwait.
so with Iran, they are a HUGE threat with their nuclear technology. they probably won't attack Israel directly, but will continue to support Syria, Hezbollah, and Hamas like we already see them doing. when/if this does happen, the entire world knows that the US will come to Israel's aid.
and the problem with that is the Russia and China are being very quite. they are even stoking Iran's fire. they WANT Iran to war with Israel (which would mean war with the US) because they each want to be the world's superpower. and with each other's cooperation and weakening the US through wars in the middle east, they could accomplish this. so the BIGGEST threat to the US right now is Russia and China. Putin is one of the most wicked world leaders in power today, just nobody wants to talk about it.
the one good thing about Saddam, as wicked as he is, is that he knew how to keep the other muslim countries in check. no one ever heard a peep out of Iran after Iraq pretty well crushed them in the 80s. but with him out of the picture, Iran has quickly come back into the forefront.