The music is unique both in its epic scale and in its sound world... Wagner’s role in the evolution of music is crucial. His mature language is a rich-textured, multi-layered sound, full of detail but never confused. He uses a large orchestra, not just for its brute force, but for the range of colours it offers. And he pushes the bounds of tonality to the limit. Undoubtedly, the most talked-about chord in all music is the so-called “Tristan chord”, from Tristan und Isolde. Isolated, it doesn’t seem to be alluding to any key. And when Wagner resolves it, he lands on another chord that leaves the music lingering, suggesting longing, or maybe ecstasy, or maybe death prolonged.He pushes the bounds of tonality, but always with dramatic and emotional purpose -- unlike many of his predecessors, he was prepared to take music where it needed to go to express the emotional extremes; and unlike his followers, he understood that atonality must always be tied to its emotional purpose. His music was uniquely expressive: there is nothing else like it.
Read: What Is It About Wagner? - Stephen Pettitt, The Times.