We printed our wordpress blog. The book quality is good, however the photo quality is horrible. If you have multiple photos on a page, blog2print uses the 100pixel wide thumbnails and blows these up to page width. It turns most of your book into a game "guess which photo this was", with you only able to see see large pixel blocks.
Contacted tech support and even gave them the solution (they just need to remove the crop parameter from the image URL before importing the photos). Support was very unhelpful and gave suggestions that are not possible in wordpress. After a month of emailing they got sick of me and the finally gave me a full refund.