Nostr users, how does this differ in your experience from Mastodon? At first glance it seems like the same idea but with the extra ingredient of blockchain, I'm not sure what this adds though, anonymity?
You start by creating a pair of public/private keys. That is your "account" but is independent from everything else (e.g. not tied to any specific tool nor web service).
Then you create texts (notes) which are digitally signed with your private key. Using the public key anyone can verify it was you writing it and nobody else.
There is no blockchain in the process, these simple text messages get sent to a multiple number of relays (you can even host them yourself) and other people can read them very freely.
The main difference to mastodon is that exists no central server where someone registers an account and has the power to kick you out from the site (deplatform). This also solves the problem with the mastodon servers decides to stop the service and suddenly everything is gone.
On NOSTR your texts are your texts, and there are multiple copies everywhere (more than 1000 free relays at the momment).
So with Nostr - it's decentralised to the point that I'm (me the user) the individual point that's sending et, rather than Mastodon which is decentralised less such that there's multiple servers with many users.
So you can always download and read them easily. I'm an old person from the forum days and was really annoying that whenever a forum would go down, all the useful posts and info shared over the years would disappear too. With this kind of mechanism, it is easier to rescue that data.
NOSTR isn't just about twitter-clones, it can basically be used to replicate blogs, forum and chat apps that exchange messges.
On Nostr the server is just a dumb relay, it controls and owns nothing. User identities are proper public key pairs. If a relay goes evil, you can just use another one or use multiple at once to begin with, since the location of the messages is irrelevant, everything is held together by public keys.
Though, they did happily filter Macau casino spams flooding the system, so I wouldn't be so sure. Workload of posting to and receiving from dozen servers was also not trivial when I was trying it out, and architecture changes to reduce duplicates and/or syncing databases across hosts were actively discussed. I guess those works were never completed judging by comments here?
On Nostr your account is your signature so there is no such thing as creating an account on someone else's database. You push to multiple relays where people can follow you so even if relay operators ban you there will always be some relay willing to host your stuff.
Others already pointed out there is no blockchain involved other than using the same secp256k1 as Bitcoin for signatures.