Word it is polycarbonate, not "cheap plastic."
First, we have no idea these renders are the actual release of the phones. With regard to design, Nokia has been a little schizophrenic, bouncing from the curved to the sharp corners. Releasing phones with and without the aluminum band. I did love my 920, but sport a 930 now and it screams premium look by comparison. But neither is perfect and I have had issues holding both, overheating of the 930, and poor battery life on both, often fixed by firmware or a reset.
Not sure these phones will make a statement as it seems everyone wants. However, they will be ready for Windows Hello, Continuum and seem to sport hefty batteries and decent storage with MicroSD. Many of these things users have been shouting about for years. Hopefully gone are the days of 4GB handsets that allowed 64GB added storage while a flagship like the 1520 on a major carrier was stuck with 16GB and no expanded storage. Another example is the 1020. Who in their right mind decided to put a 41MP camera in a phone with no expanded storage???
Don't get me wrong. I am loving my current Windows Phones, and I am even rocking the latest W10 build on my daily driver with only a handful of inconveniences and issues. But really, Apparently the squared corners did not attract that many customers, and a more generic, but stylish look might just win the day. I do think for once there will be some takers for Windows Mobile. We'll see. If not these, the maybe the fabled Surface Phone.