From two days ago:

https://lemmy.ml/comment/13108576

A few SimpleX shortcomings beyond what you noted, in no particular order:

• No multi-device support.
• Adding contacts requires sharing somewhat large links (as either text or QR code) which can be inconvenient.
• Messages are lost if not retrieved soon after they’re sent. (I think it’s 21 days by default. I’ve had vacations longer than that.)
• No group calls.
• Group messaging is full-mesh, meaning that as a group grows, the network traffic will balloon faster than it would with any other topology. This is generally bad for high-traffic groups, but it might be okay if they stay small or everyone always has great unmetered connectivity.
• The claim to not have user IDs is misleading at best, and outright false in group chats.
• The desktop app uses Java, which will be unappealing to more than a few people. (To be fair, several other messengers use Electron, which is also unappealing to more than a few.)

It does have some neat design ideas. I don’t consider it ready for general use, but I look forward to seeing how it develops.