I was never a big proponent for DPP. I use/used Capture One, RAWShooter, Lightroom, ACR, and Bibble. However, owning one of the first 1D Mark III's, I had few choices, at first, when processing RAW.
I've become a convert. Maybe not for everything, but certainly for the last few jobs. The DPP conversions seem cleaner and more detailed (at least with the Mark III). I did conversions with Lightroom, DPP and ACR on a recent editorial shot at 800 ISO. While the recorded white balance in DPP was ever so slightly redder (on skin tones), the images from DPP seemed snappier and sharper. (Yes, I apply a small amount of sharpening when processing ANY RAW files in ANY program.) While I love Lightroom's interface and plethora of adjustments, I loathe that I have to "import images" before working with them. I have no desire to use Lightroom as my DAM, but am forced to, at least in a limited way, if I want to use the processing characteristics at all.