The major interest of the book is in the chance to see the lyrics Lerner wrote after 1960 -- that is, after Camelot, after the retirement of Frederick Loewe (though he did come out of retirement for the stage version of Gigi and the flop film musical The Little Prince). The last 25 years of Lerner's career were a series of misfires, but they were all misfires with something to recommend them: basically, they were shows that could have been good if anybody had been able to stand up to Lerner and make him write better, the way director Moss Hart made him write better in My Fair Lady and Camelot.
So On a Clear Day You Can See Forever had a great score -- the composer, Burton Lane, was even more talented than Loewe -- but a wandering, incoherent book from Lerner. At that time, at least he had the excuse that he was heavily dependent on injections from Dr. Feelgood; such things might make anybody's writing a little incoherent. But Coco (1969, music by Andre Previn), 1600 Pennsylvania Avenue (1976, music by Leonard Bernstein), Carmelina (1979, music by Lane) and Dance a Little Closer (1983, music by Charles Strouse), all had the same problem in various degrees: some very good things dragged down by some obvious flaws that Lerner either couldn't or wouldn't fix. Dance a Little Closer wasn't a bad idea -- a musical version of Robert Sherwood's antiwar Idiot's Delight, updated to the nuclear age -- and some of the Strouse/Lerner songs were good. But some of the things in it were just incredibly awful (an unfunny character based on Henry Kissinger; a gay-marriage plot that was bravely ahead of its time, but so badly done that it may have set the cause back by two decades), and Lerner reportedly never even acknowledged that anything was wrong with the show at all. His problem was that while he was a talented writer, he was an erratic one who needed to be kicked in the butt before he could give of his best. After Hart died, and after Loewe retired, there was no one around who could dare to kick the My Fair Lady guy in the butt; Burton Lane came the closest, and that's probably why Lerner's lyrics for Lane are his best post-Loewe work, not only in On a Clear Day but the mostly charming Carmelina.
The other thing you notice in reading these lyrics is that while Lerner could be a wonderful lyricist when he was at his best, he was unbelievably terrible when he was at his worst. After My Fair Lady he became an Anglophile and more or less lost the ability to write good lyrics in colloquial American English; this wasn't a problem in Gigi or Camelot, but as time went on, Lerner's lesser stuff started to sound like a very bad Gilbert and Sullivan imitation, and his tendency to idiotic doggerel came out at the worst times. So in Lolita, My Love, his disastrous musical version of Lolita (the show, with music by John Barry, closed out of town and never made it to Broadway), here are some excerpts from the opening number, "Dante, Petrarch and Poe":
To a nymphic-driven man like Poe or Dante Alighieri,
Ordinary love is, all in all, too ordinary.
How can you compare a woman's Chase-Manhattan charm
With dusty little toes, a sticky hand, a scrawny arm?
Dusty little toes?!
A dimpled flank, a bony shoulder
Sink into the flab and disappear when she is older.
...QUILTY (to Charlotte)
Who is that viper
Who likes them post-diaper?
Or this exchange from 1600 Pennsylvania Avenue, Lerner and Bernstein's well-meaning but brainless meditation on race issues in American history:
Did reason or compromise help you to write
A negro shall equal three-fifths of a white?
Three-fifths or two-thirds?
Stop playing with words
Or, James, you will sleep on the sofa tonight.
You cannot deny
That little white lie.
I shan't even try.
For slavery seemed to us all at the time
A minor concession and hardly a crime;
Pre-destined to die.
Pre-destined to die!
I'd like to know why
That little white lie
Was destined to die?
That whole number (called "The Monroviad") suggests a Ken Burns documentary rewritten by Ogden Nash on a bad day.
Lerner also had a tendency toward grammatical sloppiness; even his best songs can contain lines like "Up with which below can't compare with," or Henry Higgins singing "hung" when he really means "hanged," or the most ungrammatical line ever sung by a character who's supposed to be a grammarian:
I'd be equally as willing
For a dentist to be drilling
Than to ever let a woman in my life!
Then, of course, there's Lerner's famous misogyny; in My Fair Lady this was not a problem because he could channel it all into the character of the misogynistic Higgins, but in later shows the misogyny sometimes came out "pure," and at inopportune times, in lines like:
I must have her.
I must have her.
I am still a man of honor
And to force myself upon her...!
I would rue it.
But I'll do it.
I must have her. (Carmelina)
When your lover flies away,
Sad are they who learn
There can be a darker day:
Her return. (Coco)
At the time of his death, Lerner had signed to write the book and lyrics for The Phantom of the Opera, and had in fact completed a lyric for "Masquerade" (after he died, Andrew Lloyd Webber had a different lyricist write a new lyric with the same title; Lerner's has never been released to the public). If he had written Phantom, it's pretty clear what the result would have been: a flop with some interesting and worthwhile things, side-by-side with some awful things that Lerner never fixed.