nostr shouldn't be used for secret convos like you would use signal or matrix for. at least not yet. there is still alot of info about the conversation that is exposed in the metadata and there isn't any forward privacy. though there is work on-going for both of these issues.

Nostr encrypts messages, but it doesn't hide information about messages. This is what it looks like if you check messages after signing into astral.ninja with Darthcoin's public key

Now on other messenger applications this or more data than this is what other messengers look like to the NSA. So its all a matter of perspective.

All the "secure" messaging apps have tradeoffs. Privacy and security are not booleans. Nostr is miles better than Twitter DMs but I would be very careful. Content is encrypted as other has mentioned but not the parties.

Simplex Chat is the best secure messenger I have seen, none of the others come close

They know who, and when you are talking. Just not what. That's less than ideal. Matrix is pretty cool, at least I think so. I have no real threat besides just enjoying privacy, though.

Signal for most communication due to seamless integration between desktop/Android and voice call capability when needed. I see nostr as a social media tool and that is why i haven't really used it much. I don't see it as a personal communication tool, do you think that is the wrong way to look at it?

Signal for some comms.

Por ahora no creo que sea seguro utilizar Nostr para mensajes privados, ya que si tu clave privada es filtrada tendrían acceso a todos tus mensajes.