Especially with a (mostly) consistent global user interface such as OS X, users get used to doing things a certain way. The same way your fingers know where the "x" or "t" keys are on your keyboard, the neural pathways used to access commonly used elements of a user interface are strengthened every time they are used. This builds a motor memory that is extremely useful in day to day work, but the same thing that makes our lives easier can also cause issues when something we have some to rely on in the way we use our computers changes.
Almost all the Mac users I know have at some point reached for F9-11 when working on a Windows machine, only to realize that Exposé is gone in that environment. Imagine that tonight magical elves sneak into your house and change the layout of your keyboard to DVORAK. It would drastically slow down your typing, and hinder your over-all use of the machine. According to David Malouf, Principal Product Designer and board member at the Interactive Design Association, "When using a convention that is so well grounded it is difficult for users to begin to imagine how they might use something, even with the simplest alterations. They have become accustom to the cues and signals that are learned from previous use and if there is too much similarity between the convention in the new context with that of the old context, there is little to help them to adjust to where the convention is not held to."
One would assume a design and usability conscious company such as Apple would keep this in mind when developing the software millions of people use every day. Unfortunately, with iTunes 7, the boys in Cupertino seem to have forgotten some basic rules of human computer interaction.
Lets play a little game. Open up iTunes and start playing an enhanced podcast; that is to say, one with multiple chapters. Now, try and find the chapters menu. Where'd it go?
It's likely that the next thing you do after discovering that the menu is missing from its traditional place in the toolbar would be to look around the rest of the interface. Perhaps down by the album art? Maybe it only shows up in one of the three views? Nope; I'll give you a hint: you won't find it anywhere in the iTunes window. Check the menu bar.
I know! What the hell!? When was the last time ANY application put a context sensitive menu or function in the menu bar? For that matter, when was the last time the you saw the menu bar functions of an application change other than when you updated the software. I can hope Apple has some pretty serious usability study data to back up this extremely unconventional new aspect of our user interface. That, or the iTunes team was in a crunch and brought on some temporary labor in the form of cocaine fueled chimpanzees.
After spending a few days ruminating on what could have possibly brought about this change, I'm still drawing a blank. Nothing about the new interface makes any sense to me, but maybe I'm just missing something.
I can only think of two possible explanations for this UI faux pas, and one is far scarier than the other. It's possible that Apple hired some new designers with some new (and in my opinion bad) ideas about where the iTunes interface should go in the future. If this is the case, I don't think anyone will hold this against them. The other possible explanation of the new design is that Apple has stopped caring so much about design; and this scares the crap out of me. Since the beginning Apple has placed huge importance on good user interaction in all facets of their product line. A change toward focusing more on money and less on design could be indicative of larger changes at the company we all know and love.