Recs.
Updated
SpecsUpdate
Pros
Pro Available as a hosted version
Avoid having to setup servers and install the codebase through RocketChatLauncher (https://rocketchatlauncher.com)
Pro Record multimedia using your computer's camera and mic - instantly add these to any chat
Pro Members can press a button to instantly embed their location as a flat map linked to their actual coordinates on Google Maps
Pro Allows configuration and customisation
You have a very complete administration backend with a huge amount of options. No fiddling in config files necessary.
Cons
Con Centralized
Rocket.Chat is a centralized server which is able to integrate or connect other servers and even other chat solutions with webhooks, bridges and many integrations like SlackBridge, Zapier, WhatsApp (Twilio).
Recommendations
Comments
Flagged Pros + Cons
Con Multiple Android apps (was: "Poor Android application")
The Android application was just a badly wrapped webview which did not perform well and had no form of offline caching whatsoever. But that's really outdated. You have multiple options and the recommended client app is written in React Native.
Con Privacy settings are absent
Privacy settings for the server are absent, for instance, you don't have the ability to disable registrations, there's no way to control access to the chat.