iPad apps bring back mid-1990s "mystery meat" user interface problems

Jakob Nielsen's iPad usability report makes interesting reading. The conclusions drawn about iPad apps suggest that developers need to pay much more attention to the user interface (or UI) of the apps in order to eliminate the mid-1990s "mystery meat" usability issues.

"Mystery Meat" is a term I remember being applied to both websites and desktop apps. It described a situation where the UI of a program or site was built in such a way that you didn't really know what anything was or did until you clicked on it. This problem, which has largely vanished from websites and desktop applications, seems to be back in force on the iPad according to Nielsen:

The iPad etched-screen aesthetic does look good. No visual distractions or nerdy buttons. The penalty for this beauty is the re-emergence of a usability problem we haven't seen since the mid-1990s: Users don't know where they can click.
For the last 15 years of Web usability research, the main problems have been that users don't know where to go or which option to choose — not that they don't even know which options exist. With iPad UIs, we're back to this square one.

I've noticed this on apps designed for the iPhone, and scaling these apps up does nothing other than make the problem worse. The problem is that it's hard to know what anything does. As Nielsen points out, touching something can result in one of five things happening:

Nothing happens
Enlarging the picture
Hyperlinking to a more detailed page about that item
Flipping the image to reveal additional pictures in the same place (metaphorically, these new pictures are "on the back side" of the original picture)
Popping up a set of navigation choices

Is there anything to give you even the slightest clue what result you'll get? Not usually. As a rule apps leave you jabbing at the screen like an ape trying, via some kind of random walk process, to figure out what everything does.

Another example cited by Nielsen is what users have to do when they reach the bottom on an on-screen article. Users might have to do one of three things:

Scrolling down within a text field, while staying within the same page - For this gesture to work, you have to touch within the text field. However, text fields aren't demarcated on the screen, so you have to guess what text is scrollable.
Swiping left (which can sometimes take you to the next article instead of showing more of the current article) - This gesture doesn't work, however, if you happen to swipe within an area covered by an advertisement in The New York Times app
Swiping up

Again, the UI offers us no clues. The real issue here seems to be that Apple's idea of a clear, clean UI is at odds with what developers what to give users of their apps. But if the user gets no visual clue as to what they are supposed to do, or what UI elements are on offer, most of this functionality can be lost.

I also agree 100% with Nielsen's suggestions as to what would make a better iPad app:

Add dimensionality and better define individual interactive areas to increase discoverability through perceived affordances of what users can do where.
To achieve these interactive benefits, loosen up the etched-glass aesthetic. Going beyond the flatland of iPad's first-generation apps might create slightly less attractive screens, but designers can retain most of the good looks by making the GUI cues more subtle than the heavy-handed visuals used in the Macintosh-to-Windows-7 progression of GUI styles.
Abandon the hope of value-add through weirdness. Better to use consistent interaction techniques that empower users to focus on your content instead of wondering how to get it.
Support standard navigation, including a Back feature, search, clickable headlines, and a homepage for most apps.