I love what they're going for! However, I really don't think that text messages are the future. Looking at things like WhatsApp, iMessage, FB Messenger and others, a company like Apple will probably drop support for them very soon. A possible fix for this would be to support 2FA apps like Google Authenticator for communicating those codes. If not, I'm more than sure that Apple will release some kind of API for services that allows us to send messages...
The code entry form is 100% broken on safari [1]. It lets me type a number, then deletes it.
The cursor doesn't move to the next field, and the number I did type flashes in and then disappears.
[1]: Version 9.1.1 (11601.6.17)
Super cool. Looking forward to trying this out for a future project