The first trichord being the prime form, the next three are, respectively, the retrograde inversion (backwards and upside down), the retrograde (backwards) and the inversion (upside down). Here is the first movement with the score:
Apart from that, I just don't have much to say about it. One interesting thing about this kind of writing is how quickly the possibilities were exhausted and even after the principles of serialism were extended to other parameters like rhythm, dynamics and articulations, how quickly that was exhausted as well. The repertoire of serialism is not really large.
The relationship between this piece and previous concertos is tenuous. It is obviously not a solo concerto in the Baroque, Classical or Romantic modes. It is more like a Baroque concerto grosso for a group of solo instruments, but without the orchestral accompaniment. This is like a crystalline distillation of music. I suppose, if you like this sort of thing, it is a masterpiece. But to start sensing that, you would have to listen to it many times. It does have its unique appeal, but despite the fond hopes of his admirers, I doubt that we will ever hear Webern's music whistled in the street.