Lete me preface this by saying I'm no musical historian, so what I say may be completely off-base.
I've been listening to a lot of Chopin lately since I'm learning two of his works right now. It seems to me that more than any other composer I am familiar with, Chopin showed very little maturation as a composer. Now, I don't mean that his works are bad. I'm saying his style of composition seems fully-formed even from his early works. Some of his earliest pieces seem to be among his most mature works. I'm thinking in particular of his early nocturnes, the Op. 18 Waltz, the Op. 10 etudes, among others. Certainly, he had many great works throughout his life, but even his early works display an unusual mature style. Contrast this with Beethoven or Brahms, for example. Their late works are very different from their earliest works.
Now, I suppose that some of this is attributable to the fact that Chopin died at a very early age. Perhaps he would have done amazing things of which we can't even comprehend had he lived until 60. Still, Chopin seems to be somewhat of an anomoly to me.
Agree or disagree?