Didn't see this posted, thought some might be interested. No dGPU option is disappointing, if expected.
http://www.engadget.com/2015/10/13/apple-imac-review-2015-21-5-inch-4k/
http://www.engadget.com/2015/10/13/apple-imac-review-2015-21-5-inch-4k/