If an iPhone user has trouble using a website, does that mean the UI is intrinsically bad?
Examples of trouble:
Here are some examples of where a website can give users trouble when viewed on an iPhone:
The iPhone has no problem scrolling the main document. But it has trouble scrolling when you put scrollbars on a modal box. There's no indication that the box is even scrollable. Many people I've talked to don't even know you can scroll a modal box with two fingers. Even then, it's really fidgety. A real life example is an admin site that a coworker made. He made all the main navigation links open in modal windows. Even on a desktop computer, i found it annoying to scroll the windows to reveal all of the content.
- Hover states
You cant hover over an element on the iphone because it's a touch based device. Sometimes you don't know what's clickable and not because some designers rely on the hover state to show that it's clickable. An example is SmashingMagazine.com. You don't know that the article titles lead you into the article because they're not blue or underlined. But on a computer, it does have a blue background when you hover over the title.
- Drag and drop
Im not sure ive ever seen drag and drop implemented on a website for iphone. Perhaps its not even possible. Drag and drop is a novel idea. It works well in some cases like reordering of items. I find that it's cumbersome in nearly all other cases. Take Google Docs for example. You can drag and drop files from your hard drive into the site. But this requires you to shrink your website to make room for the folder that has your files. This juggling of windows is a little hard for some people.