What I heard was a fascinating saga. Webern's opus 1, an orchestral passacaglia which he wrote when he was 25, is already a mature work, which demonstrates how high his standards were, and why DG should have honored them. A passacaglia is constructed over repetitions of a single bass line, and while Webern's sounds romantic (it's fully tonal, and as lush as Mahler), the bass line disciplines it, making it unfold with the same precision we can hear toward the end of Webern's life, in opus 30, also an orchestral work. Both pieces group their music into clear-cut sections, which are always derived from the same material.
Opus 1 begins with just the bass line, bare and all alone, and then continues with a quiet flute elaboration draped on top of it. Opus 30 starts with double basses, thrusting upward, followed by a quicker imitation of them in a darting high violin, though now -- here come the anagrams -- the melody is upside down.
Opus 2 is something only Webern would have called a separate composition -- it's a choral wisp, not three minutes long, lovely and retiring. With opus 3 and opus 4, Webern moved toward atonality, but the music doesn't fit atonal stereotypes of noise and dissonance. Both works are groups of very quiet songs, which stretch in new directions only (or so it seems) because they stretch emotion further, too.
But then comes a burst of more conventional dissonance, in atonal instrumental works that sound nervous, even shuddering. Webern wrote these in 1909 and 1910, when modernity, with all its shocks, was uprooting traditional stability; deprived of normal anchors, his music sounds unsettled. Ideas are scattered heedlessly, crowding into one another. Sound itself gets restless; instrumental colors, sometimes strange and strained, emerge and quickly disappear. No rules apply to endings; each work has to find its own way to sound conclusive, sometimes by falling into what can sound like exhausted repetition. (Hear this! MP3 for fast connections. RealAudio for 56k modems. It's the ending of the first of the Five Pieces for String Quartet, op. 9, and also demonstrates the wonderful playing of the Emerson Quartet.)

After that, from 1911 to the end of World War I in 1917, came crisis. During these years, Webern painfully gave birth to works that almost aren't there, tiny exhalations that don't quite end; they simply cease to be. Webern said that he felt stuck; once he'd written all 12 notes of the chromatic scale, he almost helplessly became convinced that there was nowhere else to go.
How could he get past that? First by using words for structure, allowing poetry to shape his music. From 1917 till 1927, all his works were songs, accompanied by unexpected instrumental groups (just two clarinets in one set of songs, for instance, or, in another, just high E-flat clarinet and guitar). Each line of verse, sometimes just a single word, might suggest a new musical direction; the music can be paradoxical, lost in baffling complexity, while it swoons over texts that are sometimes very simple, sometimes nothing more than folk poetry.
These works are intensely private, and radically difficult to perform, requiring hours of rehearsal to fill perhaps three minutes of a concert program. They thrive best on CD, where we can take all the time we need to savor how a single chord will dance inside a verbal nuance, then disappear when words and music move to something else. Endings can't settle into repetition, because now Webern's music is too concentrated; nothing can repeat. Instead, he'll end a song with a surprisingly obvious rhythmic flourish.(MP3.  RealAudio. This is the ending of the first song in the Op. 14 song cycle. Boulez, I think, could strengthen both the rhythm and the accents of  the ending far more than he does.)  
Or, which interests me more, he'll let an ending simply fall into place, without emphasis and yet with utter certainty, as if some unseen process had worked its way to a conclusion. Sometimes there really is a process working, a single melody unfolding many times against itself (in musical terminology, a canon). The songs where that happens are, to me, the most powerful of all, as if Webern, by joyfully accepting restrictions, could transcend himself, finding music that his ear alone would never bring him. (MP3.  RealAudio. This is the ending of the last song in Webern's Op. 15 song cycle, written, like Op. 14, for soprano and instruments. Wait for the very last note -- so unexpected, and yet so right. The entire song is a complex canon, meaning that the last pitch, along with everything else, is determined in advance, once Webern decides how to fit the parts together. Of course, he has to decide exactly where to place it, meaning in exactly what rhythm, and in which instrument. But there's a sense in which he's simply arranging the cards he's dealt by an abstract process, and he seemed to like that.)  
And that's how Webern finally found freedom, with the restrictions of the 12-tone system, whose patterns showed him what to do, once he'd used up all 12 notes: He could use them once again, in permutations of whatever order he'd used them in originally. This helped him break loose in 1927 with an instrumental work, his opus 20 string trio, in which he pantomimes older musical forms, and then in his 10-minute Symphony, opus 21, in which the discipline is even stronger, and the musical notes seem fixed in place, like stars in the firmament. Webern's rhythms now were simpler, his sounds more clear, his forms transparent. Increasingly, his works complete themselves with no external fuss, until his last work, a cantata, ends with a chorus in three stanzas, which run their course (all of them identical) and, when finished, simply stop. No composer ever finished with such economy, or such restraint.

A word on all those extra, "unofficial" works: When I finally heard them, they really were addenda, footnotes to the Webern canon, demonstrations, because Webern rejected them, of his uncompromising standards. As for Boulez, his standards, too, are high, but something's missing. When he earlier recorded all of Webern, in 1969 and 1970, some critics -- deceived by both his and Webern's reputation -- thought he'd done a perfect job. But those performances are coarse compared to the new ones; musicians, it's clear, have learned to play this music much more lovingly.
But the best Webern on the new set comes not from Boulez, but from the Emerson Quartet, whose members play the string quartet pieces on the edge of their seats and at the further reach of their hearts and their imaginations, and from pianist Krystian Zimerman, who makes the palindromes of the Piano Variations, opus 27, as lush as Chopin (something Webern would have loved; he sang and danced when he coached a pianist in that work).
Boulez isn't as convincing. He catches Webern's purity, but not his innocent emotion -- as, amazingly, it's possible not just to assert, but to document, by comparing a Boulez performance to Webern's own. Webern, who sometimes worked as an impossible-to-please conductor, orchestrated Schubert dances and led them in a reading that, by some miracle, was recorded. This performance graces the first Boulez set (still available from Sony Classical); in the more recent box, Boulez conducts the music. He sounds blank; Webern truly danced, taking the music both faster and slower, treating it more freely and sounding much more joyful. (MP3.  RealAudio.) His own works -- or so he might be telling us -- should sound that way as well.

( Note that the phrase Boulez and Webern conduct is repeated, so each does it twice. Boulez is first. The contrast, I think, is even greater than I made it sound in my review -- and Webern's performance, wildly free and sensitive, is just astonishing. I defy anyone to tell me he didn't want his own music played this way. (Don't hesitate to use the MP3 even if you have a 56k modem, if you want better sound. But the file will take a couple of minutes to download.).

Wall Street Journal, February 14, 2001