Pretty much the best reference book I know about any subject at all. I have consistently found it uncannily accurate and alarmingly complete; I have on occasions tried to send in reports but found that every single thought I can muster about a resort is already in print. It's almost sinister. It's also easy to read, amusingly rude about some places, and full of beautifully edited piste maps. I can't imagine planning a ski holiday without it.
Having got various older copies of the book, I can concur that the 2012 edition is shorter than 2008, but longer than 2011 - and the level of detail seems to keep on growing. This year there's an extension to the 'resort price index' to include lift passes; this helped me win a bet about the relative prices of Courchevel and St. Anton so it must be good.