It is possible to have both great content and great design, but it's rare. Think of the Met museum website vs a tech startup. Both will have modern, fancy UIs, but the museum also has real information where the marketing site will only have design elements and simple hype statements.

That said, you probably want to judge your bank's trustworthiness by it's rating with the Federal government, which is public info. Most banks (all but the biggest) have to outsource their online banking software and it's never as slick as the big guys'.