The short version: open banking lets a company reach its customers' bank accounts (or its own, across many banks) through one API, instead of building a separate integration with every bank — and in the EU, PSD2 requires banks to expose those interfaces, so the rails are…
In my experience the most important aspect is real bank-connectivity coverage — how many banks the platform actually reaches in your target markets, how fresh that coverage data is, and how quickly connections get fixed when a bank changes its interface. A slick sandbox and…