I really enjoyed the first third of this book, while the reader is still trying to figure everything out and before Jacob meets the peculiar children. Once the children were found, the book seemed to lose some of its originality and just became another super-hero book. Maybe it is because I just started watching season 3 of Misfits, but the Peculiars seemed mundane comic-book. Parts of the book reminded me of L'Engle's time travel (old women who turn into birds), the tone (especially in the beginning) was reminiscent of Gaiman's Graveyard Book.
The concept is great and the old pictures are lots of fun; I realize that Riggs was trying to concoct a story from these pictures that he found; but several times I felt like he was stretching things a bit. He also left it with a potential sequel ending, which just made me groan.
Overall it did not feel like an adult novel, felt more like a tween love sci-fi novel (at times better than Twilight), but overall suffered from the same problem that Rowlings has with the Potter series...a teenage boy hero with almost no sex drive (really the least believable piece of all the fantastical stuff that happens).
Update, my 9 year old son just finished 1/6/12 and he absolutely loved the book. He would have given it 5 stars. He mentioned that he is reading it to his elementary school librarian and she told him that there is a sequel coming (as I predicted). He is very anxious to read the sequel.