Aperture or iPhoto
I can't comment, but everyone asks. I only use Aperture.
In March 2008 I purchased my first hard cover book via Aperture. I was reasonably pleased with the price (a little over $100 + delivery). It arrived quickly and the quality of the paper and the images is fantastic.
It did however come with no dust jacket. But this is not a negative story. Looking back on the disk at the PDF transmitted it was missing. It is my guess that it was a bug in Aperture 2.0 that is now fixed as new PDF contain the dust jacket.
Apple on hearing the news of the missing jacket wrote a very pleasant reply and refunded my money.
So will I use them again - you bet, my next book is about to be ordered. The quality is good, the service appears even better.
UPDATE: I have since purchased 3 more soft cover books, all have been perfect.