Curious to see more of Hans von Bülow's fascinatingly cruel 1872 letter to Nietzsche, I looked it up in the Nietzsche Briefwechsel. Here is my rough translation:

But to the matter at hand: your Manfred-Meditation is the most extreme case of fantastic extravagance, the most unedifying and anti-musical instance of notes placed on music paper that I have come across in a long time. Several times I had to ask myself: is the whole thing a joke, and did you perhaps intend a parody of the so-called music of the future? Did you consciously flout all the rules of musical language, from the higher syntax to simple matters of correct notation? Apart from the psychological interest—your musical fever-product gives evidence, despite all the confusion, of an uncommonly distinguished spirit—your Meditation is from the musical standpoint the equivalent of a crime in the moral world. I could discover no trace of Apollonian elements, and as for the Dionysian, to be frank, I was reminded more of the morning after a bacchanalian orgy than of an orgy per se. If you really have a passionate urge to express yourself in musical language, it is indispensable that you acquire the rudiments of this language: giddily fantasizing on a remembered gluttony of Wagnerian sounds is no basis of production. Wagner’s most unheard-of audacities are rooted in the drama and justified by the text (in purely instrumental pieces he prudently abstains from similar monstrosities) and can always be recognized as grammatically correct, down to the tiniest details of notation; if an educated connoisseur like Herr Dr. Hanslick is incapable of grasping that much, then it is evident that one can only really appreciate Wagner if one is “musicien et demi.” If, as I must still doubt, your detour into the realm of composition is seriously meant, highly honored Professor, at least confine yourself to writing vocal music, and let words be the oar that guides your boat as you bob on the wild ocean of sound.

Once again—no offense intended—you yourself describe your music as “horrible”— it is, actually, more horrible than you realize, not in a way that is harmful to the common interest, but worse than that: harmful to you, who cannot more wickedly beat to death your excess of leisure than in this kind of rape of Euterpe.

I could not contradict you if you were to tell me that I have overstepped the outermost limits of civilité puérile. "Please regard my unapologetic frankness (rudeness) as a sign of my equally sincere respect"—I refuse to let this banality bring up the rear. I simply have to give free rein to my indignation at such music-averse tone-experiments: perhaps I should turn a portion of that indignation on myself, insofar as I am responsible for having brought Tristan to performance once again [Munich, June 1872] and thereby am indirectly guilty of having sent such a lofty and enlightened spirit as yours, very honored Professor, into such regrettable keyboard spasms.

Perhaps you will be cured by Lohengrin on the 30th . . . [Various other dates for Wagner performances follow, and Bülow ends with a conciliatory remark about Nietzsche's "magnificent book," The Birth of Tragedy.]