[bztzt]

Yeah, I think setting the default file associations to Metro apps is something that really damages people's first experiences with Windows 8 on non-tablets. I find it hard to believe that many people, even "casual" PC users, would prefer this setting, at least with the apps in their current state (which I doubt will change that dramatically by launch). It is easy enough to change (there's even a popup that appears the first time you open a file of some type, asking if you'd rather use a different app) but a standard rule of UI design is that most people don't and defaults do matter.

[momotomo]

I think if someone's running a majority of metro apps it might be a bit less jarring (because they are used to the "app as the whole screen" thing), but it can be confusing when switching, and the switch feels a bit like everything else has "closed" if you're used to the task bar. The windows key acts as a good anchor though, everything feels pretty close at hand.

I do like that quick little context box for the other installed apps. Advantage to how that app selection context box works is that it scales with the users expertise - if you do see it, it means you've installed software, which probably means you understand why the selection is necessary. Average mum and dad user probably won't come across it / get confused by it.