It's good. I use it (dual-auth with FB) in a production system (https://www.voo.st/) and it works great from every browser I've tried so far, including iOS and Android.
The biggest UX issue is currently the up-front email roundtrip for new accounts. In the long run this experience will improve considerably when primary identity providers support the protocol directly. In the short run it's still not bad.
The biggest UX issue is currently the up-front email roundtrip for new accounts. In the long run this experience will improve considerably when primary identity providers support the protocol directly. In the short run it's still not bad.