I'm upset that he hasn't done more for civil rights. There's still way too much sexism, religious bigotry, oppression of gays, and racism. Just as a matter of policy, bigotry is still the status quo far too often. I'm also disappointed that he didn't follow through on his plan to boost education. He had a much better plan for that than Hillary did, which is one of the main reasons I supported him and not her.
It would be pretty cool to have an actual left wing politican to vote for in 2016.