Well, there are a LOT of pictures, the coolest of which is a photo of Bono and Pope John Paul II with JPII wearing Bono's shades. (I remember Bono saying the Vatican refused to release those pictures so Bono has gotten his "revenge" now that the Pope has left us.)
There are some adorable shots of the band as young boys, and with their families, although I have seen some of them on PLEBA. And then of course tons of photos through the years.
As for the text, the book starts out with essays by each band member and they are completely in character. Bono's sounds exactly like him, meaning that it rambles. Edge's is thoughtful and articulate, and in parts hilarious (he writes how at age 5 he suddenly began to resemble Alfred E. Neumann on the cover of Mad Magazine -- and there's a photo on the next page that shows that it's true!) Adam tells us he never wanted to be anything but a rock star, and Larry basically says, I became a drummer because I couldn't do anything else.
The book itself is divided in chronological chapters, and it is very front loaded on the early days plus the years up to Pop, but disappointingly thin on the past 10 years. In that, it's a lot like Bill Clinton's book -- remember he wrote at length about his childhood and really rushed through the last years of his presidency. Music Rising, for example, is stuck in on the very last page.
As far as style, it resembles those Vanity Fair oral history articles or the "Bono on Bono" book. It's not really a narrative, it's blocks of quotes from each of the band members. It almost reads like they were interviewed separately and then the quotes assembled per subject.
I'm only just scratching the surface -- it's a pretty massive book.