App is generic. Store is generic. App store is therefore generic.
You can destroy almost every trademark that way.
I see many comments saying "App Store IS generic". This "IS" isn't an argument no matter if you use capitals or not.
1. What is a "generic term"? Do we base this on the pervasiveness or the correctness of the definition or what?
a : relating to or characteristic of a whole group or class : general
b : being or having a nonproprietary name <generic drugs>
c : having no particularly distinctive quality or application <generic restaurants>
2. Let's look at pervasiveness. It doesn't matter if the term was used before Apple got it. This isn't about patents. One fact is that Apple clearly made the term popular. A problem here is that the App Store was basically the first one with such influence, so, obviously, everybody started using the term. But that doesn't make it generic in the sense it cannot be trademarked. Same like iPod.
Let's look at the definition. Is App Store the best description? Hardly. First, why would "app" be generic and not "application"? Or "program"? The easiest would be just to call it "software" and it will be the most correct definition. It was created for that purpose. What about "store"? Generally it refers quite much to a specific closed physical place. Market would be much more correct. So, "Software market" will win correctness-wise.
3. Why do you think Microsoft is doing this? Saving the language? The App Store has attributes to it - Apple made it popular, people generally expect some level of quality, range of apps and whatnot. Apple build this. It would be very easy for Microsoft to use the same term and thus make people attach to their products attributes which Apple created. Not very nice.
4. I surely am not a lawyer and I can be wrong, but the issue clearly isn't that black and white. And I side with Apple, because no matter if the term is generic or not, Microsoft's intentions are very clear.