yeah, I've used DigitalDaVinci before. I made a photobook for my sister's christmas present last year. Looked really great
Although I did find there were quite a few "spats" of black ink on some pages, which was a little disappointing, but nothing major.
They're pricey, but I was happy with the result. They have a plug-in so you can order the book through iPhoto rather tahn emailing them a PDF, but it's for iPhoto 5 only.
ALso they don't support the new features found in iPhoto 6 yet (calendar/greenting cards).