Thanks Darren for posting this. I've given it a go and compared to Nikon's View NX2 its a real winner. It can do everything and more NX2 can do but with a lot more control. Also it handles NRW Raw files, the new format that Nikon just decided to start using on their Raw capable compacts. Most software can use this so you have to convert it first in NX2 which means you cant non destructively manipulate the Raw file. Capture One does and its a lot faster too. For Free its a blinder considering how much you have to pay for software like Lightroom and its added capability.
I like CaptureOne a lot and use it to process the files / capture images from my PhaseOne backs. I have CaptureOne Pro 6 (although it is free for use with their backs) and might end up switching to it from LR once the integration with Media Pro becomes more comprehensive as I usually use things like Nik from PS (launched from LR) rather than directly from LR and so wouldn't lose these.