works offline

Huh, that's curious, that sounds impossible to make properly secure, since if you're not verifying the validity of transactions with some trusted third party or ledger (I think it's called that in crypto), someone could make a transaction, and then locally rollback their state to make another transaction to somebody else, which wouldn't actually be valid.

I'll have to read up on it if I remember, maybe it's just half-offline, in that you can sign transactions offline if the other party is online to execute them?

Generally though, whether it's "good" tech is a rather ambiguous question - I think it's a good concept that has some ethical problems and big issues in practice, including social aspects of how it's used. I think most people on the fediverse value decentralization to some degree, so a world where crypto didn't end up being mostly used for speculation and scams could've been interesting.