I'd like to start off by saying I'm not "Left" or "Right" I am for common sense approach to politics. I really don't see a whole lot of the "Left" coming to defend Obama with "Bush this Bush that". I almost didn't post anything because your post came across a bit arrogant. Thank you for giving us permission to answer without the "Right" chiming in. Thanks teacher for giving us a "homework" assignment. You are so kind.
I would also like to say, I think this question is being posed a bit to soon but the following are what I feel to be accomplishments and for the greater good for the American people and the World.
1. Most importantly he became our President of this United States of America.
The following is an excerpt from ABC News, Political Punch that I thought put his campaign in perspective.
He beat the premiere Democratic machine, a former First Lady who remains popular with Democrats and is married to the most popular Democrat (among Democrats) in the US.
He beat her among women.
He beat John Edwards in union households.
He won among Democrats who said Iraq, Pakistan, health care, or the economy were the most important issues facing America -- despite Clinton attacks directly on those subjects.
Despite claims by rivals that he only appealed to effete elitists, he won every income bracket but one -- $15,000-$30,000 -- which he tied with Clinton.
It was an astounding achievement.
And, by the way, he's a black man with the middle name Hussein, and he did this in a state that's overwhelmingly white and Christian.
Hurray! Proves our ppl are bigger dolts than anyone imagined.
2. Biggest infrastructure investment since the interstate highway system in the 1950's.
Way to keep the construction lobbies and their illegal employees in work. Did anyone see any construction jobs in the want ads?
3. The biggest investment in education in a generation. Including fixing the No Child Left Behind act.
Typical liberal response to failing programs... throw money at it.
4.
Kissing arse world wide.
Had to fix that for you. 
5. Addressing the home foreclosure crisis.
After helping cause it. Notice there is no more talk about that? Brushed under da rug.
6. Introduced the Strengthening Transparency and Accountability in Federal Spending Act of 2008.
Now there's a contradiction in terms, if I ever heard one!
7. Boosted U.S. Troops in Afghanistan to stabilize the region.
But he still hasn't caught bin Laden like he promised.
That is just a handfull of things I could come up with. I put this together rather quickly, I haven't had time to be on the computer today but I'm sure some can add to what I've started.
