Trump said that Kamala's acceptance speech was very poor, because she spent too much time thanking people, something of course which he'll never be accused of. But then again, Trump probably thought that it was a little 'light' as well. After all, his acceptance speech was 92 minutes long while Kamala's was only 38 minutes. BTW, Trump's speech was the longest on record. Note that the old record was held by Donald J. Trump, his 2016 speech was 75 minutes long.
And while Kamala's speech was considered shorter than average, there were many past candidates with much shorter speeches, such as JFK's 22 minute acceptance speech in 1960. But she did tie with two past winners, Eisenhower in 1956, and LBJ in 1964.
And another statistic: during Trump's 92-minute speech, he said "I" 262 times, while Kamala only said "I" 83 times. That being said, the actual RATE at which they said "I" was close to the same. Trump: 262/92 = 2.85 "I's" per minute. Harris: 83/38 = 2.18 "I's" minute.