I have it. Just not many contacts there.

Privacy wise it is better than anything else, but it is also harder to use (joining groups, managing contacts, etc).

The network privacy caveat was already mentioned - simplex proto does nothing to protect a powerful attacker from linking you with a specific simplex server (AFAIK neither does any other chat protocol?). If this is a concern then you need to use large/public simplex servers (or rely on TOR, etc).

There is one other aspect specific to the public servers, which is the room directory service. When you add your groups to the directory you are inviting a bot into the group, so DO NOT expect these to be private.