As a teacher, my gut reaction is to hate apps that do not follow the HIG.
I understand Tog‘s argument about GUI quote-unquote “bandwidth” which has expanded enormously over the past 25 years. However, it still isn’t ubiquitous. There are still a lot of new users. We could generalize and say something terrible like “It’s all just old people, so the problem solves itself” but that isn’t true. It is estimated that only 2 billion people are using personal computers. UI patterns are important. I don’t think anyone would deny that. I would further argue that it is still too early to abandon standardized UI elements. The “bandwidth” isn’t there yet. There is still value in the HIG, at least in low-level, system-wide contexts.
That said, I think the iPhone and iPad might accelerate the abandonment of standardized UI elements. But first, I must digress.
Computers are not machines. I mean that in a mechanical sense. You cannot punch a few buttons and pull a lever and have the same output produced time after time. Computers are problem-solving devices. Everything depends on context. That is why step-by-step lists of instructions fail so often. Problem-solving tools and concepts are key (cf. Tog’s point of recognizing differently shaped houses). Every day computing is an exercise in problem-solving.
To return to iOS: when 3rd party apps were released I was appalled at all the crazy interaction metaphors that were being used. Every app is different! Talk about ignoring the HIG. However, limitations due to form factor and capability constrain the types of things that can be done. Even though iOS UI conventions are pretty loose people can make sense of it. And much quicker than they do on regular computers. This is brilliant because they can take these skills to their desktops and figure out what is going on there.
iOS devices are giving people the right problem-solving skills that will help navigate other UIs, hastening the demise of things like the HIG. Also, think about the future of mobile devices in markets overseas where traditional PCs are not accessible. That is class of new user that could benefit from not being saddled with HIG-encumbered historical expectations like we have.
In the end, the HIG is just a guide, shambling along. I agree with John’s argument that it is there to serve in situations where a better UI pattern cannot be executed. I think it should be adhered to for basic, system-wide functionality for the benefit of new users, but abandoned when a more effective alternative is possible.