The AMD Radeon RX 470 for laptops (RX 470M) is a mid-range graphics card for laptops. It was announced in August 2016 and is based on the Polaris 10 chip, just like its bigger sibling Radeon RX 480. The GPU does, however, only use 2048 shader units (32 CUs, 128 TMUs) from 2304 (36 CUs, 144 TMUs). The clock speeds look to be similar to the desktop version of the RX 470 (at least in the Alienware 17, see GPU-Z screenshot). Therefore, the performance should be on par with a non overclocked desktop version.
The performance is similar to a desktop GeForce GTX 970 and a bit slower than the newer GeForce GTX 1060 (mobile) and should be faster than the previous top model M395X. Modern games from 2016 can usually be played in the Full-HD resolution and the highest settings.
The TDP of the desktop Radeon RX 470 is specified with 120 Watts by AMD, the mobile version should be a bit more power efficient due to selected chips.