This version of the Wicked Songbook is the one that DOES NOT have the melody interpolated throughout the piano part-- it is meant as a "vocal line with piano accompaniment" version. It is described by Stephen Schwartz in his forward to the book as being "essentially a reduction of what is played by the show orchestra, edited so that it is playable by one person with two hands and ten fingers."
The songs have been adapted so that they may be sung out of the context of the show, with longer instrumental sections, chorus parts, and other such material being trimmed out in most cases. Though this gave me pause at first, I am learning that it really serves the material in this sense, making the music perfect for performing on its own, out of the story-driven context of the show. (Some cuts include the 'We Deserve Each Other' section of "Dancing Through Life", and the 'Who's that Mage...' counterpoint in "One Short Day")
All the favorite songs appear here, from "The Wizard and I", to "Dancing Through Life" and even an excerpt from "Thank Goodness" entitled "I Couldn't Be Happier". There have even been some small additions to the songs to make them work better for solo performance-- I love the new added verse in "No One Mourns the Wicked", for example. It makes for exciting rediscoveries of these already familiar pieces.
The arrangements are challenging, yes, and except for in one case all the songs appear in their original show keys (which means, e.g., that "Defying Gravity" is in Db, "One Short Day" is in F#, etc, but are well worth the effort-- both those songs sound amazing. "For Good" has been taken down a half step and appears in the book in C major). For those trying to compare this book to the P/V/G (with melody) version, I would say there is NOT a huge difference in degree of difficulty between the two books.
The wonderful result of this effort is that the arrangements are SO true to the score. It's really encouraging that Hal Leonard is starting to let composers publish more accurate and exciting versions of their work, and that what we get in the vocal selections is not some cheap simplified thing that sounds nothing like the nuanced and complex score but instead is actually rich and fantastic and interesting.
These Vocal Selections are without a doubt some of the best I've seen produced. Huge congrats to Stephen Schwartz for getting out the music in such a way that the core of the score really is still intact and ensuring that the great songs from this show will be performed for a very long time. Just Amazing.