Well, if they could just extend this to every meet&great everywhere, this would clear up a constant battle between DW and I. I like my kids interacting with the characters, but I always feel the actual signing wastes time and takes away from the overall interaction. I've argued us down to 1 book that the 2 kids share, but zero books would be even better.
Also, my wife actually makes each book, which adds to her stress of getting ready for the trip, which adds to my stress, which I don't like.
I have to admit, I did like seeing the signatures the first time around, but after a while, it becomes repetitive.
ETA: I should also point out that for the characters we have come across that don't sign, there wasn't a single bit of disappointment from my kids (or my wife) which leads me to believe they could live without the autographs...