I'd like to qualify the enthusiasm I've expressed about the quality of C1 conversions. I don't want anyone to get the wrong idea.
I'm a bit of a control freak about the look of my images. Always have been. It's all about the print. I used to spend 8 hours in the darkroom when I was in graduate school (a "few" years back) making one print - cutting rubylith masks, selective flashing of the paper, exotic developers, selenium toning, waxing the prints, the whole nine yards. There is an inverse relationship between the amount of extra time spent making the print and the gain in quality. If I doubled the time to make the print, I'd get maybe 25% more "quality". If I quadrupled it, print "quality" would increase only slightly - and so forth. But that extra investment in time has always been worth it to me. To me, time doesn't exist, only the print. If I can increase "quality", it's worth doing, no matter the cost in time or effort.
In evaluating C1 software, I judge the results the same way. To me, any increase in quality is worth it. The edge artifacts that Peter refers to are only a part of the story. With C1, there is an increase in surface texture, depth and dimensionality that I judge to be similar to what you get from a drum scan; it is better than what ACR is capable of giving you. It's not an earth-shaking difference if your perspective is from afar. But, for better or worse, I obsess over these things from a very close point of view and the difference is obvious to me.
Don't think that a side-by-side comparison of prints processed in ACR and C1 will give you one blue one and one yellow one. They'll be extremely similar, possibly indistiguishable unless you get REAL close. But I DO get real close, and, to me, the difference is worth it.
So save your money (C1 is $500). Unless and until, of course, it's worth it to you. A fully functional 30-day demo version of CaptureOne Pro is available at www.phaseone.com