* Everything is a "workflow" and you often find yourself stuck in some terminal error state for no reason.
* No JSON, everything's a page load.
* ...or, if there is JSON, it's done badly and you have an unholy combination of janky SPA functionality across multiple pages.
* Arcane timeouts
* "Disable your popup blocker"
* Insane data validation errors.
* Poor SSO integration.
I could go on.