Maybe I can help:
I feel Signal is doing a lot right and if I need to send a message right now and be 99.999% sure nobody except the recipient can read it, Signal is my choice.
My criticism is mainly directed not at Signal, but at the people trying to promote Signal by trying to trash every other messaging technology.
The reason is that until Signal solves:
- backups
- stable API available for everyone (I don't think they have one)
- bots (I mean a bot API for creating bots)
- large groups
- a number of ux issues
- and allow armed forces and other groups that need it to run their own servers
... until then there will be room for other messaging solutions.
I'll take it a step further:
- if you would be happy to stuff it in a physical envelope
- or send it by email
- and you don't hold a grudge against Facebook or are willing to live with the thought of FB knowing who you talk to and when
then you can safely send it by any messaging service.
Fighting about which just keeps people using sms or email, both trivially interceptable by a number of parties.
TLDR:
1. Signal is fine, excellent AFAIK
2. there's room for other messaging services as well
3. one doesn't make Signal better by trying to trash other messaging solutions