I love it!
Yes, it's pricey considering you're never going to get coupons like you will with the more popular services. A 100 page book will cost you about $100. But if you use iPhoto to organize photos, it's way too easy to make and print a book straight from the program.
Tim and I have mainly used this service to make gifts for the parents so far. The very first book we ever ordered was an awesome Christmas present that was 100% Tim's idea! His parents are avid gardeners and have a gorgeous garden, so I took some photos during the summer and we later made those photos into a book for them!
My mom loved the book so much that she requested that I make a book of the cruise that her and my dad took with their moms to Alaska last year!
I also just recently finished making a book from our wedding (I know, five years later!!!), and printed books off for Tim's grandparents and for my mom's Christmas present.
The only book that we've ordered for ourselves so far is our 2012 book. We love it! Being able to drag and drop photos straight from your library is just so easy!
The quality is great; as long as your pictures are decent. And when even your iPhone photos are good enough quality to be printed, you shouldn't have to worry.
So in conclusion- yes, iPhoto books can be more expensive if you are the type to wait out for good coupons, but for the lazy people like me, they are easy, fast, and good quality. I need to order our 2013 and 2014 books soon!