@Hypolite Petovan I do not want to be in the position of a #Matrix Advisor, since I see both positive and negative sides.

There are a lot of advantages, like it's a distributed, open standard, open source system with lot of native clients (including the most used web or electron based one), approaching the UI from various directions. It is technically a distributed, directed acyclic graph of JSON messages, but the most prevalent use is as a next generation IRC (internet relay chat for the newborn kids): a massively multi user multi channel chat with reactions, images, sound, colors, full history and whatnot. It is supporting both cleartext and end-to-end-encrypted channels ("rooms") natively. It is really simple to write bots or automated means to handle messages as well. Soon-ish there going to be threads, bychance.
Matrix needs no personal data for registration, no phone numbers or like; it depends on the specific servers whether they ask for any kind of verification or not (my server asks for email, others are fine with a solved captcha, it depends).
Supports audio and video chat (p2p with native protocol or group chats using Jitsi).

The disadvantages are more peculiar. The organisation behind the standardisation process has a leader not dissimilar to OpenBSD (maybe not that smart like TdR), so contributors sometimes get scared away by the harsh style, and often the externally originated PRs aren't accepted. The standard is often not updated with features live on the network for even years. Also there is one server provided by the org which has unproportionally lot of users, so the network is not as distributed as it ought to be. This also cause friction since the org enforces its own view of social interaction standards on their server and the rooms managed by their employees, and often they ban people for no good reason.
The E2EE mode is still somewhat hard to bootstrap for unexperienced users, since the background tasks aren't visible, so often it doesn't seem to work while it's really just still bootstrapping.
Audio/video chats are still full of rough edges and many clients simply do not support it. Group encrypted video chats are depending on the jit.si e2ee support, which is coming, but not yet there.
The clients are somewhat resource hungry and the initial synchronisation is rather slow (due to protocol quirks).

Security-wise it's a pretty good network. For non-fixed groups of people (where people are expected to come and go, new people join later etc.) it's much better (feature-wise) than Signal.

For closed group chats (like family, friends), especially where there are a lot of direct chats Signal is clearly more performant, easy to use and ubiquous.