UI--saying it is stone age is being kind. As a DOS and Apple II survivor it triggers me. Visually it looks like back when you had to load hard disks in to use language programs. I did a double take the first time I saw it, it looked almost exactly like the first language program I used in the 90's.
Visually it looks like it hails back from the 20th century, it is clunky, a challenge to use it with different devices.
It's a nightmare, however I'm stuck with it because the the language course I'm taking, a multi year program, has invested a lot of time putting their program on it.
The idea of wrestling with Anki for another two years is absolutely depressing.
In two weeks I've had to reset my password every time I switched devices, seven times! I've had to remove and reload the app four times. It takes forever to upload the school's decks. I dread when a new deck comes out.
It doesn't sync with my mobile device. It's made me change the password every time I try to switch between devices and doesn't recognize the password, which I know is correct. So I just have to anticipate changing the password if I switch between my ipad, phone, or desktop.
Basically, Anki has trained me not to use my mobile devices which limites my ability to study.
I could go on.