Bought it in 2017 and still using it. With a 5.7 inch 720p display, and windows 8.1 ( Present Os Wondows 10) , it includes features such as live tile, amazing color profile, wide viewing angle, low power mode, and much more.
Above all basic features, it is the Camera that helps it stands out from other phones. With a 13 megapixel Camera with Zeiss Optics, provide features like Ruch Capture, Dynamic Flash, and Backside-illumimated image sensor. It captures decent details, and it does a pretty decent job in terms of managing light and maintaining image quality. It also captures high-quality full-HD video with good audio quality. Not only rear camera but also the front camera is perfect for good quality selfies, even in low-light conditions.
Like nearly all Lumia phones, it is the battery life and camera performance that makes 640 XL stands out.