Pixel C reviews are pouring in, and they're all virtually the same: pretty awesome hardware, but Android on tablets just isn't any good. The Verge:
But the performance issues, the lack of apps, and the lack of split-screen functionality show that, right now, Android isn’t really even trying to participate in that future. Simply put: the Pixel team has mostly delivered something really good, the Android team has not. Android may not be Google’s answer for the next generation of computing on a tablet. Maybe that will have to wait for whatever weird hybrid ChromeOS / Android thing that Google is supposedly working on.
iOS and Windows are both much better suited to a larger form factor device. Maybe some day Google will implement that "experimental" multi-window mode, which will help. However, right now it's selling a $650 tablet/keyboard combo that can display a single app at a time. Even with a hypothetical split screen mode, you'd still have to deal with a sea of phone apps from developers that are reluctant to implement a large-format layout, in part because even Google doesn't take its own tablet platform seriously.
They're all right, of course. That being said, it's clear the Pixel C isn't really intended as a mass-market product - at least, not right now. No, the real purpose of the Pixel C is to serve as a development device for Google's Android developers, who are currently, by all accounts, working hard not only on combining Android and Chrome OS, but also on bringing more traditional functionality, such as multiwindow, to Android.
Android is movin' on up, and the Pixel C is nothing more than the ladder Google's Android developers need to get there.