I was having an email discussion with Ben Slivka the other day, and he asked me what three things were going to make customers enthusiastic about Longhorn.
My answer to him was as follows:
I'm not sure. My guess would be the changes around the Multimedia experience (persistent per application volume control, and improved handling (you can have windows sounds be mp3 files), WinFS means that you can search the metadata on your multimedia as quickly as you can Google, which makes slicing and dicing play lists better).
The new UI should be REALLY slick, and should attract a lot of consumers (eye candy always does).
Beyond that, I'm not sure - the reality is that most of the cool stuff in Longhorn is plumbing - Avalon and the rest of WinFX means that app authors will be able to easily do stuff that they've never been able to do before, which means that there's a host of new cool apps that will be able to be written for longhorn. That also means that app authors have even more ways of writing annoying applications (if you think skins are bad, consider what happens when app designers will do when they can put video on a button face), so...
But the thing is that consumers don't see the cool stuff that's going on in the platform. Unlike Apple, who spends HUGE amounts of time and effort on making the UI cool and flashy (and responsive and consistent, etc), Microsoft tends to work on getting the plumbing right. But customers don’t see the plumbing.
Which means that our toilets flush and our sinks drain really, really well, but they're not very pretty. To continue the plumbing analogy, Apple is Kohler - lots of flash, looks great, works well, Microsoft is Delta - not as much flash, but totally rock solid reliable.
The reality is that I just don’t see customers going totally bonkers about things like the games library or parental controls, or the other end-user features of Longhorn. But man, Longhorn as a platform is going to let developers do really amazing stuff.
Please note: I’m not an evangelist. I don’t know all the bells and whistles; I work on windows audio, which is why my answer was multimedia-centric.