Well, it's not a big problem, because most of the bank apps still work, but they rely heavily on Google Play Services. It can partially be solved with a separate profile and Graphene's sandboxed Google Play Services, but still a bit annoying :(
I also like the convenience of using Google Wallet to pay for things. It's by far the fastest transaction and easier than futzing around with chip cards and pins. It's also more secure than the dumb tap to pay bullshit in credit cards themselves which do not require biometrics or pins. (Currently my main card is too old to include tap to pay, so I don't have to worry about how to disable it yet). Just generally Google Wallet is more secure than chip+pin while also being much easier to use and not having to trust some random keypad.
It's also nice to not even have to carry a wallet around. I'm not fully there yet (Apple supports my state's drivers license but Google Wallet support isn't ready yet). Phone is obviously something I take with me, it just makes wallet so vestigial since Apple Pay/Google Wallet support is becoming very ubiquitous.
My banks have also implemented 2FA login by just push notification so no typing number or such tedious stuff. Unlock my phone, pass biometrics and done.
There are more but those are just the first things that come to mind.