When the Daily Dose of Septuagint went over Genesis 2:18, I had a small realization about "it is not good."
Then the LORD God said, "It is not good that the man should be alone; I will make him a helper fit for him." [ESV]
As God surveys creation in the previous chapter, "it was good" (or some variation of it) appears seven times (in verses 4, 10, 12, 18, 21, 25, and 31). Because the negated "it is not good" in 2:18 breaks this established pattern, it stands out more and seems to receive some emphasis.