This has some additional music from The Piano (some of my favorite themes from the soundtrack, although they don't translate as well on piano as the first book).
Additionally, the songs that are in both books are "cleaner" in this one: Big My Secret and The Heart Asks Pleasure First both feature easier to read (but identically played) notation.
The Piano is one of my favorite soundtracks and sounds difficult but isn't TOO Hard to play on the piano. It is very moving music and I really enjoy playing from both books.
But, Big My Secret and The Heart Asks Pleasure First are the most important pieces and they are in both books, so if that is all you like, no reason to buy this one too.
OH! One thing I was confused about is it is called a "pocket manual" I have NO idea why. This is a normal sized piano sheet music book. There is nothing "pocket" about it.