I hate when things are 'assumed'. As in, the pattern writer assumes the reader knows how to make certain basic blocks. Over the last two years, I have been part of our guild's BOM committee. I have learned that many participants want their hands held the whole way and/or are so new to quilting that no instructions are too basic to be left out.
I too, am a visual learner. I love illustrations. And I suppose I am also an audio learner, since I tend to understand directions better when I read them aloud.
My biggest pet peeve is the omission of one very important distinction in many patterns or directions. That distinction is the 'finished' or 'unfinished' size of a block.