5 stars: Not as easy to use as WhatsApp - yes, but it's getting there. The added benefit is that it's open source and you are in full control of your own data. Also Element is the only full-featured FOSS alternative to Signal with the important difference that you can host your own Matrix server.
5 stars: For something less known and providing a UI to a federated system Element has come a long way. Ignoring the length of a username its to the point really anyone can start using it. There are some minor improvements possible but I'm enjoying using it with my family.
5 stars: One of the best FOSS tools I use. This is a fantastic chat application for a fantastic chat platform. If I may make one suggestion, I would love to be able to sign in to multiple accounts simultaneously. Thanks for all the hard work!
4 stars: A few bugs, sometimes I can't see messages in group chats, and it takes much longer to send messages than other E2E chat apps (Keybase, Signal.)
5 stars: Great app, and it's only going to get better as both it and the matrix protocol mature. It's already a lot more customisable than the alternatives. 1min to register and get going, and you don't need to provide your email nor phone number. The only downside I could find is that email notifications are on by default. It caused some annoyance to people that are less technologically apt, and so they needed help to find the correct settings.
5 stars: Excellent messaging app. Works well, very encrypted....