I may be a Xenakis fan, but I won't take up a cudgel. Xenakis DID write a lot of music that just wasn't that good from a purely aesthetic perspective, but he does have some works that are quite pleasant, and those works are to be found on both ends of his compositional life, in my opinion. There is an early set of piano pieces called Trois Chansons which is very nice. Also, his latest works, such as Keqrops, Aïs, and many of his percussion works (late or not late) are quite good and don't require ears of steel to listen to. The thing I really enjoy is the amount of energy and rhythmic innovation present in a lot of these works. The reason why most people here dislike his music is purely because his most notorious works (the ones most people have heard) are simply the most strident ones on the ears, such as Synaphai, Evryali (I still love this work), and Herma. Just give the works I recommended a try and you will enjoy some of his music.