This is still my stuff.

This is a huge subject, and Alex Ross does a great job of covering it. Not everyone will be happy if their pet composer or movement has been tackled only briefly (if at all), but it would be impossible to fit the entire century into a single volume. As a result of reading this I have been moved to listen to Schoenberg and Strauss (esp. the Metamorphosen) for the first time; they are challenging works but rewarding and it has been great to have my musical horizons expanded by reading this book.
For me, the book was worth buying for the chapter on Sibelius alone; the passage describing the walk around Ainola and linking it to Sibelius' music is just superb - it sent me straight back to my CD collection to dig out and listen to the symphonies after years of not playing them.
Overall that is the most wonderful thing about this book - it inspires you to listen to more music.