Specific criticisms of GPG:
> the working hypothesis for privacy enhancing technology was simple: we’d develop really flexible power tools for ourselves, and then teach everyone to be like us... Instead of developing opinionated software with a simple interface, GPG was written to be as powerful and flexible as possible. It’s up to the user whether the underlying cipher is SERPENT or IDEA or TwoFish
I think it's self-explanatory why it's not good that users need to know about SERPENT, IDEA, and TwoFish.
> the fundamental architecture of PGP also leaves no room for now critical concepts like forward secrecy.
> a ballooning penumbra of OpenPGP specifications and notes so prolific that the entire picture is almost impossible to grasp... Mailpile had to write 1400 lines of python code just to interface with a native GnuPG installation for basic operations, and it still isn’t rock solid.
> journalists who depend on it struggle with it and often mess up (“I send you the private key to communicate privately, right?”)
UX failure leads to user uncertainty or insecure behavior.
What a better replacement looks like (from the comment here):
> Good UX requires thinking about interactions all the way down to the protocol.
> we can start fresh with modern cryptography, a modern protocol, and a modern design philosophy