Good questions. I was looking for a "phone side". To make, or receive a call you have to use two hands to open that thing up and use it? Is anti-ergonomic a design? How can you see who's calling? Even something as simple as the time we've all had since the 90's? Missed messages? Voicemail waiting? Any type of control, or info, requires you to open up the tiny laptop? Or you have to basically wear a Bluetooth headset at all times? Wow, that would be awful. Even the flip-phones of yore allowed you to see who was calling without opening the phone and, opening just required a flick of the thumb. Perhaps there are some indicators under the front/back of the closed body that we just don't know about?
I'm not being anti-microsoft, but it looks like someone just brought back the netbook.
Don't work for Apple/MSFT/Google, but have knowledge of usage data for various smart-phone OS's: you'd be surprised at how _calling_ has become a minor use case across the board when it comes to smart phones.
It's now a "feature" that primarily caters to power users: if you use calling, you use it a lot - otherwise the user tends to use messaging / texting / other medium (like FaceTime.)
Therefore my design guess is that Microsoft is aiming for the video call / bluetooth headset, and will take the hit in terms of awkwardness for holding up to your ear for some calls.
I'm not being anti-microsoft, but it looks like someone just brought back the netbook.