From: Charles Rosen. Critical Entertainments. p. 117 Bottom - 118 Top.
In the same way, attacks on Beethoven could be profound and even persuasive, and would continue to be so after his death even to the present. Most musicians (outside of Central Europe) will appreciate the brilliance of Debussy's remark at a concert during a Beethoven symphony: “Ah, the development section is beginning; I can go out and smoke a cigarette.” The way Beethoven's reputation was “constructed” is perhaps revealed best in some comments made in 1812 by a close friend of Goethe, the composer Karl Friedrich Zelter:5
“I, too, regard him with terror ... His works seem to me like children whose father is a woman or whose mother is a man ... I know musical people who once found themselves alarmed, even indignant, on hearing his works and are now gripped by an enthusiasm for them like partisans of Greek love.”
A few years later Zelter was to become the teacher of Mendelssohn, who would take the latest and most difficult works of Beethoven as models for his own compositions, but in 1812 Beethoven was a monstrosity for Zelter.
Am I right to infer that Debussy judged these development sections boring and unworthy?
Even if yes, how's this judgement 'brilliant'? Isn't it churlish and cheeky?