The problem with Signal is the savior complex of its creator, who insists he and only he can correctly implement secure messaging, and it can only be done if he's permitted to handle all your data himself.
He is basically saying the same as people who said "Let's accept self-signed, and broken SSL certificates, or "the unwashed masses" will not understand." Remember how it went.
> Remember, IT security doesn't have to be absolute.
The field of applied cryptography is absolutely reliant on near physical unbreakability of its algorithms, or it doesn't work at all. (you need n-times the life time of the universe to have a working bruteforce, and as much overwhelming mathematical proof of non-applicability of non-bruteforce approaches as possible.)
And it was actually found to be extremely hard to make crypto algos which are only "slightly" unreliable. Either they are a complete mathematical iron wall, or their deemed weakness is too glaring to be hidden.
Well... if E2EE is properly implemented, you could be broadcasting your messages on twitter and you'd still be safe.
Many people were angered by the recent update that forced users to have pins, which many didn't want. Doubly so since there's no recovery method.
The pin issue highlights that future updates could make things less secure and/or add backdoors. Various legal efforts in various legal jurisdictions are trying to enforce backdoors and it remains to be seen if whisper systems will pull out of a jurisdiction if forced to compromise on security.