He's pretty moderate policy-wise. His big one's probably abolishing the electoral college (which I can't see happening) and giving Washington DC and Puerto Rico statehood. Otherwise it's stuff like getting a single-payer healthcare option to compete with the private sector, working with unions and taking antitrust and the digital economy seriously, getting back into the Paris agreement and subsidising solar panels, a pathway to citizenship, withdrawing from Afghanistan but staying in Syria, leniency towards weed and background checks for gun owners. Agree or disagree (I'd expect the latter more often than not lol) most of that stuff's pretty incremental.
As
@Ellicottraven said the main thing that strikes me is the way he carries himself when he speaks. He seems a lot more willing to reach out and collaborate with the other side than most, and his approach seems to be a lot more win-win than Trump's win-lose philosophy. As I said earlier lot of a president's power is in their public image and I'd love to have someone like him addressing and representing my country.
He also seems a lot more electable than a lot of the other candidates, so that's why I was curious about what the centrists and moderates here think.