Well, I'm extremely excited that insurance companies can't drop me because of pre-existing conditions. I'm also very thankful that there's no more lifetime cap on what my insurance can pay. I think it's great that they're increasing the amount of aid for health insurance for low-income people. And the coverage for kids up to 26 is good.
The stimulus plan was a huge deal. Many, many economists argued that with out that the US would have sunk into a depression.
Obama's endorsed same sex marriage and appointed many gay officials, which is a pretty big deal (though more work needs to be done).
Ended the policy of torturing people.
Proposed and signed the Dodd-Frank Act, which while it's pretty watered down, at least tries to prevent another financial collapse.
Followed through with pulling troops out Iraq.
During his tenure and with at least some help from the US, Gaddafi is dead, there was the Arab Spring, and Osama bin Laden is dead. All of that with out launching a major invasion.