It is a fact that it takes a long time to assess the importance of any composer. We are too often blinded by our enthusiasm for a contemporary composer, and assume that they are more important than they actually are. For example, I am completely convinced that Donatoni will be be remembered as one of the greatest composers of the late 20th and early 21st centuries, but to honest, I can't really see beyond my own enthusiasm. I can make an educated guess, but only history can judge.
Stravinsky occupies a strange place in history. There is absolutely no question about The Rite of Spring: it is one of the cornerstones of music, a turning point in music history, and a masterpiece from beginning to end. But remarkably, our enthusiasm for the Rite has completely subverted any kind of objective assessment of the rest of Stravinsky's work. I read a series of comments about Stravinsky lately from some of my colleagues, and absolutely every comment seems actually to be about the Rite: "exciting music", "changed music forever", "rhythmically revolutionary." Yes, some of these comments apply to other works by him, but really, when we talk about Stravinsky, aren't we really talking about the Rite?
I recently tuned in to his Symphony in E flat major, a work he wrote when he was quite young. I was impressed with how completely he had absorbed Rimsky's influence, and I was dazzled, as always, with the orchestration, although in the Symphony what is dazzling about the orchestration is how textbook perfect it is. But the work is not imaginative.
I like much of the Firebird. I am largely indifferent, even slightly hostile towards Petroushka, although many people I respect very much consider it to be his best work. From the post-Rite years, I adore the Octet, I enjoy L'Histoire in suite form, I like the Violin Concerto, and I worship the Symphony in C. The first movement of the Symphony in Three Movements is one of the finest pieces of music written in the 20th Century. The second and third movements are simply awful. The ending is genuinely sleazy.
I conducted the Piano Concerto with a well known soloist several years ago. He opined that no one plays it because it is so difficult. I pointed out that no one plays it because it is terrible music. Terrible, terrible music.
The Septet is a genuine abomination. The much-touted serial works are just bad, with the exception of the Requiem Canticles and The Owl and the Pussycat, where the old Stravinsky shines through. No one can tell me that Movements for Piano and Orchestra is good music. It isn't.
And yet, we have a Stravinsky cult. A few years ago, it became fashionable among European new music types to assert that serial Stravinsky was music of the highest order, better than his early music. Nonsense. In fact, I challenge the very notion that Stravinsky was one of the great composers of the 20th century. Certain works of his are undisputed masterworks, and his influence was and is tremendous, but as a composer, I strongly suspect that most of his work, once the dust has settled, will disappear. This is in contrast to the composers he is most often compared to, Bartok and Prokofiev, whose music is now so deeply woven into standard repertoire that it is impossible to imagine concert programming without it. Think about it: what Stravinsky do we actually hear regularly on orchestra concerts-- or for that matter, on any kind of concert? The Rite, The Firebird, sometimes Petroushka. Maybe the Symphony in C or the Symphony in 3. Maybe, maybe the Violin Concerto. Compare that to the regular appearance of Prokofiev concertos and symphonies, and Bartok concertos and the Concerto for Orchestra, not to mention the quartets.
Stravinsky asserted that he was a journeyman, taking work as it became available, doing the job as well as he could. I believe this is a perfect assessment of him. That he was capable of greatness is undeniable, although it seems to me that most of the greatness is early in his career. But his catalogue is such a bizarre mixed bag that a complete assessment of his achievement seems to me to be impossible.
Time will tell.