Yes, Obama did pledge unflinching support to Israel. Yes, he did assert that Iran will not be allowed to obtain nuclear weapons. No, this doesn't represent major change to US/Israeli relations. However, he also explained why ending support for Israel wouldn't solve our problems. He also explained how he would use firm diplomacy to discourage Iran, with much specificity in fact.
He also told AIPAC directly that Israel shouldn't be expanding settlements into new areas they agreed not to. He explained that a contiguous Palestinian state should be created and created in a way which will allow them to prosper. That wasn't booed, but it definitely wasn't met with roaring applause either. A lot of people need to chill out on looking for gotcha moments. Obama isn't going to radically change everything about the United States and its policy.
He doesn't wish to and won't have the power to, should he become president. But he has laid out plans for reasonable changes during his administration which appear beneficial and attainable. Just because he isn't proposing as extreme changes as Ron Paul doesn't make him a liar who is playing up the change slogan with no intention of following through.
Israel (AIPAC in particular) is so firmly entrenched in American politics and foreign policy, there is no politician running for office that can't
accept or support them. It's when that person becomes president is where that support can change.
Though in my time (Nixon, Ford, Carter*, Reagan, Bush I, Clinton*, Bush II) none have...
*Carter was close, Clinton too...