I agree with all of the above feedback regarding your ID and presentation.
The purpose of the project is much larger than just creating a phone concept but rather also to carry out the MS brand and surface experience to mobile users. Stay a bit more with the story of Microsoft rather than ‘some’ other brands. The original idea of Surface was to create novel and multi-user touchscreen interactions within the paradigm of natural user interfaces. If you stuck with that you would have ended up with a much more innovative concept I feel. The Surface Pro books stick with the idea of a very flat device and the ID is very distinctive, reminding a bit of the old Olivetti devices. Simple features like creating a thin outer edge even if the device is thick creates a much thinner appearance, something home video player device designers already faced decades ago. Your current concept I don’t think fits the project and I would like to see much more focus on interaction, focusing on a large touchscreen. Then you can consider doing something innovative, like adding a removable physical item that you can use to either interact with the screen or for NFC applications, in line with the tangible interaction paradigm although it can easily feel too much belonging to Nokia’s design thinking. Keep exploring. For concept presentation purposes, you can especially dive deeper into rendering more realistic materials, for the rest it works.