To clarify, their business checking uses a separate app from their personal savings. The business app is fine and does everything you would want such as mobile check deposits, transferring money, enabling/disabling debit. It also shows the balance on your other accounts and when you click on them it will either ask to open the web browser or the corresponding mobile app. They also have a high mobile check deposit limit of $50K/day.

I still maintain a free business checking account at my local bank so I can deposit cash and receive the occasional Zelle payment. But I prefer Amex since it has no transaction limits, incoming wires have no fees and I earn interest.

I also wanted to add that their Business Checking is iOS only for the moment.