That’s been the gist of it from my experience too. The biggest arguments against him are that he’s a “radical” with his ideas (which have been implemented to varying degrees of success in many many other countries) and that he’s an admitted socialist, but then a LOT of America’s infrastructure is socialist in nature.
People support Bernie because as different as his ideas are they do have evidence of having worked elsewhere and he’s actually been able to outline how to make them work here, and because he’s consistent. What he’s saying now is pretty much what he’s been saying for decades, which is something that none of the other candidates can really claim from what I’ve seen.