I’ve used JSF when it was still beta. It was chosen by an external “architect” as the front end for a big site with millions of views (he was anticipating that JSF would be come popular, and a big project with it would be good on his resume).

Salesforce (classic) is JSF.

It’s full of bugs and quirks. But it’s kind of nice in certain situations.

The big problem here is performance load on both client and server. State is sent back and forth and it that kan be huge, and needs to be deserializes, altered, and serialized back again every action. It also doesn’t reflect any http verbs. Everything is POST

The big site was technically running on JSF, but in such a way that it wasn’t JSF any more