PC Perspective is one of the few websites that managed to get their hands on an AMD Radeon Pro Duo card, you can check out their review over here. While the dual-GPU Fiji was initially aimed at gamers, AMD later changed its story and positioned the card as something for game developers and VR content creators. Looking at the performance figures, there seems to be good reason for this as the card performs rather poorly, which is undoubtedly the reason why so few tech sites got the opportunity to test it.
For professionals looking to get an AMD multi-GPU configuration in their machine for development and offline rendering, the Radeon Pro Duo is an ideal solution. It takes up less space but also offers the same performance capability, and it might be easier to talk your CTO into a single expensive GPU than a pair of less expensive ones! With no similarly high-performance option from NVIDIA on the market, as there was never a dual-Maxwell solution sold, AMD has this market all to itself (for now). I do hope that developers find a way to integrate this card or any multi-GPU combination into their boxes; that is what it will take to get multi-GPU into DX12 and VR games. Experience with multiple graphics cards will undoubtedly equate to better solutions for gamers in the future.