iMessage only works on iPhone and has a limited maximum group size, so for many activist movements it is unsuitable. The app does quite well on privacy and security aspects, but is not open source.

Popularity #

Apple does not disclose statistics for the popularity of iMessage. It is only available on iPhone.

Functionality #

Pros:

• Mentioning specific people: yes ✅
• Inline comments: yes ✅
• App for desktop: yes ✅

Cons:

• Group size: It is not quite clear what the maximum number of group chat participants is, but some users have reported a maximum of around 25, which is quite low ☹️
• Admin features: none ☹️
• Broadcast messages: no ☹️
• Disappearing messages: no ☹️
• Group invite link: no ☹️

Security and privacy #

Pros:

• End-to-end encryption: yes ✅
• Trustworthy owner: yes ✅

Cons:

• Open source: no ☹️
• Metadata collection: yes ☹️
• Verifying contacts: no ☹️

Price and revenue model #

iMessage is free to use on iPhone. Apple makes its primary profit by selling their devices and services. By offering apps like Signal, Apple hopes to lock users into their ecosystem.