In a sense, you're both correct. It really depends on the user and the UI annoyance. A lot of UI quirks become second nature to power users and they don't even

In a sense, you're both correct. It really depends on the user and the UI annoyance. A lot of UI quirks become second nature to power users and they don't even notice them, but things like lagging on a keypress, etc, is probably going to be a persistent source of annoyance. iPhone users, for example, don't seem to mind life without a back button. It becomes a fact of life and users adapt their usage of the device accordingly. On the other hand, when I updated my iPhone 3G to iOS 4, the responsiveness of the UI suffered by orders of magnitude. After more than a month of usage, I still found things like typing a text message excruciating. (Mostly fixed with the 4.1 update, praise god.)