Surface Phone makes sense, but I wouldn't wait for it
Nokia is doing an incredible job helping to increase Windows Phone market share throughout most of the world. Market share in Europe, Russia, China, Brazil are all way up thanks to Nokia Lumia. However in the US market Windows Phone is still losing share to Apple. The US is the one market where Nokia has no cachet and their relationship with carriers is weak. The world loves Nokia, but in the USA we love Apple and to a lesser extent Motorola. These are unique aspects to our market so it makes sense that Microsoft would once again build their own device here (like they did with Surface, Kin, Zune, and Ultimate TV). Microsoft is increasingly becoming a hardware and services company. And the Microsoft brand is becoming increasingly important in the US market as the company opens up hundreds of retail stores throughout the USA. Assuming the Surface Phone runs Windows Phone 8, then it is a significantly different product than Kin, Zune or even Xbox. It will be compatible with a larger ecosystem rather than competing with it, just like Surface tablets are a small part of the larger Windows 8 ecosystem.
But people shouldn't wait for the Surface Phone. Who knows when or if it will actually get released. Surface Phone definitely isn't coming out this year and it might not be out until next Spring. It probably isn't going to be sold outside of the USA and it likely will only be sold in Microsoft Stores, possibly even without carrier support. It might have a newer processor, but it won't have a camera as good as the Lumia 920. This may be Microsoft's Nexus phone, but it won't have the advantages of no OEM skins or the latest versions of OS. So what is the real value of the device other than to appease a country that isn't enamored with the Nokia brand? Unless you really need a kickstand and vapor magnesium case what is the point in waiting?