There are several different printing services available online that you can use to print photos, photo books and placing your photos into other formats. If your member of the Amazon Prime, you already have unlimited storage space for all your digital photography images so obviously this is a natural progression of service that Amazon would like to be able to provide you. Especially since, that customers in the US are expected to spend $2 billion or more for online photo printing services this year reported by market research firm IBISWorld.
It appears that Amazon is using a company called S&D Print as the actual printing arm of the service. You go to sign up you'll be presented with the following screen. When you accept the service you are linking your Amazon pay account with the S&D Print account.While this service is just starting out, which is apparent by the limited number of options that you have to choose from, their photo printing prices seem to be in line but the book pricing was to be a little exorbitant.
I have used Shutterfly in the past it was always very happy with the results and they have a large number of options, not only for printing photographs and photobooks, but putting your favorite photos on many types of objects and formats.
Companies like Shutterfly have a big lead on Amazon in this category and it will take Amazon a lot of effort to catch up but Amazon has all the right tools in place to be able to eventually create a viable product that people want to use. However, given a choice between Shutterfly and Amazon Print, right now I am firmly implanted with using the former rather than the latter.