I have a few CenPho-based graphic designers as friends. They swear by Impact, and I can understand why.
After the design for my business cards was ready to go, Impact treated my (let's face it -- SMALL) order as if it was as important to them as it was to me. I appreciated the attention to detail, and I now have an education in just how many different white card stocks there are, how many different shades of black ink there are, and how the two elements complement each other.
Seriously, as my business expands I hope to use Impact more and more.