Ya, because maybe the iPhone is the best example of exactly what he's talking about. The iPhone has always been something of an enigma to me. In all of the short-term usability testing I've seen (and done), it's performed really poorly. Yet the overall engagement is through the roof.

I would argue it's primarily because the iPhone feels like a game when you play it. It rewards you for doing the right thing. It provides a lot of feedback. It's smooth and quick... It's exactly what the author is talking about.

He also talks about the success of a plugin system, like iApps, in shrinking the skill pyramid.

It did seem very MS vs Apple, but it's true that Apple's walled garden prevents those later explosions on one of the 10% peaks.

The iPhone has been around for several years, but it seems there have been no such growth in it. Each app is self-contained, and is explicitly forbidden from becoming a new center.

I think his comment about the iPhone is highly appropriate in this case; while it's generally got good user experience design, there are definitely cases where the UI is built in a way that will frustrate users. Two examples come to mind from back when I still used my iPhone:

1. Undo. Who is ever going to discover this on their own? Every action you can perform on your iPhone (With the exceptions of volume adjustment, going to the home screen, and locking the screen) is done by interacting with the screen. The undo gesture is not only hard to discover by accident, but it's very context-sensitive, which means if you do it by accident, it may not do anything at all. This is basically the complete opposite of discoverability. His 'skill atoms' example should demonstrate why this is problematic - if you want the user to develop a skill on their own, it should be easy for them to discover the verb to trigger the action (press a button, tap an interesting thing) and easy to understand the results.

2. The home button. While it's convenient and useful, in many cases I would find that an application would discard my changes if I hit home to dismiss it, instead of saving them. The most common case where I ran into this was the alarm application: I'd create a new alarm, go into the subview to set up the alarm, and then hit home to dismiss it instead of hitting the little back button they shoved in the corner... and it would throw out my new alarm. While the home button is a good affordance, it is destructive - by using it incorrectly, the end-user may or may not lose work, which makes them wary of experimenting. (It's my understanding that Android has a similar issue, but I've yet to use an Android phone).

I could also harp on how the lack of multitasking increases the penalty for end-user mistakes, but people have already beaten that dead horse.

Just to be fair, here's a similar example from the Palm Pre:

In most Pre applications, to delete an object, you simply pop up the dialog to edit it, and hit a trashcan icon. Simple. However... in a few specific cases, somebody on their UX team decided it would be brilliant to require the use of a gesture to delete. There are zero on-screen cues to suggest that it's possible to perform this gesture, or that the gesture will do anything - so the uninitiated user will simply think 'how do I delete this?' and get frustrated (or, hopefully, look it up on Google). In these specific cases, you have to drag to the left or the right on top of the object you wish to delete, which magically reveals a hidden pair of buttons under the object: Delete and Cancel. Only then can you delete. Even worse, it's possible to botch the gesture - if you don't drag far enough, the phone ignores your gesture. Compared to the majority of the Pre's UI (which is light on punishment and encourages exploration), this is a huge design failure.

Can you elaborate a little on the subtle compatibility issues you've found?

Sure, here's one. ppt files with elements that don't work the same on mac and PC. Fonts changing size, elements moving around. These problems make the Mac and PC Office users avoid collaborating. Also, because the releases are are out of sync you also have to use the least common denominator file format and mac owners are the lusers. Not much fun in a startup where everyone is bringing their own tools to work.

Call me paranoid, but it feels like Microsoft doesn't really like Mac users. Kind of odd since Office is a important franchise unto itself, but now maybe they have caught on. Another example of one business silo hurting another.

Thanks. I try to use Power Point as little as possible, but I've noticed some font issues between Win and Mac versions of Word too. Not surprising I guess, but none the less annoying.