* The workflow to use your software is so unintuitive I've had to learn it by muscle memory
People don't mind when a nice discoverable UI adds some more features. They don't like it when a horrible poorly thought out one that they had to painfully learn is suddenly different. That button that used to be hidden in the edit menu? Now it's on a ribbon menu which has to be expanded. Good luck hunting!
An interesting lesson is to visit a user site and notice the step-by-step instructions, written out and taped to the sides of monitors, or pinned to cubicle walls. Those instructions were often hard-earned, either written by the user or shared among workers. That stuff becomes obsolete if the software changes. Likewise for online instructions, such as blogs that give instructions in the form of screen captures and text, and that are no longer valid. If the unofficial instructions are better than the official ones, or more legible than the GUI, then it's a step backwards for users.
* The workflow to use your software is so unintuitive I've had to learn it by muscle memory
People don't mind when a nice discoverable UI adds some more features. They don't like it when a horrible poorly thought out one that they had to painfully learn is suddenly different. That button that used to be hidden in the edit menu? Now it's on a ribbon menu which has to be expanded. Good luck hunting!