If you are on a Mac, Raw Developer may also be something to consider. It is about the price of C1, but the tool set is closer to, and in some cases surpasses Capture One Pro when you are looking just at quality of raw conversions. I am debating between those two right now and the images that I really take the time to work on are unquestionably better with RD, but I can get an acceptable image instantly with C1. If I had the funds I would get C1 Pro and never look back.
I'm trying to figure out which is better between C1 and RD right now. What I am finding is that I can get better conversions with RD, but can get most of the way there very quickly with C1. I have been running tests between them and accidentally lost the files and had to redo the test of about 100 pretty difficult images. When I realized this I was I so annoyed and really couldn't stomach the thought of taking the time to redo the images in RD, but redoing them in C1 didn't seem like that big a deal. That seemed pretty telling. As Jono pointed out, everyone needs to decide for themselves at what point it is "good enough."
The other advantage to C1 is you can start with the plain version and upgrade to the Pro version at any time for the cost difference. I think that's pretty cool.
Regarding Doug's claim about C1 speed, I have experience in Lightroom and ACR working on tens of thousands of images on deadline and consider myself pretty proficient with the Adobe workflow. With just a couple thousand images experience with C1, I would say that I am at least as fast on it, and it absolutely flies on my lowly Macbook, making field work a real possibility.
You need to understand what C1 is and what it is not. It is more than just a raw processor, but far less than a do-it-all program like Lightroom. If you are using C1, you still need to pair it with some other app for DAM.
I really wanted to like Aperture after all of Jono's comments, but neither my Macbook nor my aging (antique?) desktop have the power to run it. Lightroom runs ok, but not great, but I work pretty slowly on Lightroom on anything less than about a 24" monitor.