Powered by the same GPU as the Nvidia Shield and a couple smart phones and chromebooks, (and not as powerful as current gen consoles or even close to gaming PCs), the Nintendo NX will use the Nvidia Tegra as a GPU/CPU combo for a handheld console with detachable controllers. It will also come with a home base that you can plug into to play the console on the TV. It will still play cartridges.
My guess is that it will look like the Wii U controller, except with detachable nunchuck controllers on the sides. I would photoshop something to look like that but I need a new photo editing program. ehh.
The Tegra is a decent chip, but I don't see Nintendo competing with Sony or Microsoft at this point anymore. Its like they are doubling down on their handheld market, which makes sense to me. They know how to make good handhelds and they sell. But if this is all true it seems a bit too gimmicky to me. The Wii and Wii U was all targeted at families and party games, but this is obviously targeted toward individuals and solo players. If the screen is the normal size of a cell phone and its meant to run games all the time, I wonder how hot the thing will get and if it'll need to be recharged every 2 hours.
Sources: http://www.eurogamer.net/articles/2016-07-26-nx-is-a-portable-console-with-detachable-controllers http://www.vg247.com/2016/07/26/nintendo-nx-is-portable-with-detachable-controllers-and-uses-nvidia-tegra-tech-report/