Works great and sounds great. Compared directly with a Dragonfly Red on my MacBook Air, I heard far greater air, space and depth and more realism in voices and instrument sounds. It was like switching from a billboard picture with about 3 feet of depth to a three-dimensional window into the performances.
I also purchased and installed an internal MSATA drive and loaded 6,000-plus tracks into it. My Air doesn't have enough internal memory for all those tracks, many of them in HD formats, so the Flow enables me to access my library in a relatively portable device.