Personally, i've never even attempted Infinite Jest, but, given how much I like his other writing, i'll have to try one of these days.
A commenter on the JoS post relates this hysterical story from her Amherst alumni magazine:
One woman took his creative writing class when he came back to teach at Amherst. She said she continually mixed up further and farther. After correcting her several times, he finally wrote in the margin where she had repeated the mistake, "I hate you".