I know @bumi and @Alby have done a lot of work with it. @cascdr uses it.

Today at least, it seems most useful if you expect 3rd parties want programmatic access to a paywalled http resource or anticipate consumers will access the resource in a context that's L402-aware. While it still makes sense, it makes a little less sense where the application has accounts and other forms of authentication afaict.

For our paid stuff when it's paid non-custodially, we have a bespoke flow through graphql. We could use L402 for these but I prefer to build initial things to meet UX requirements rather than interoperability ones, and good UX demands a large degree of awareness/statefulness. I can imagine us moving to using L402 when we understand everything we'll accomplish with payments and want a more generic abstraction.