Does your partner make a specific and unique argument about how effective Thoreau's arguments are?
Do they make specific supporting arguments that help you understand why they are making their claim?
Is your partner giving direct evidence (words, phrases, lines) from the text as evidence for what they see Thoreau doing? Do they explain that evidence?
Does your reader explain the rhetorical strategies and historical context for each argument they are discussing?
As a potential member of your partner's audience, do you feel that your partner is writing for you? How could they do a better job of keeping you in mind?
Is your partner's work organized? Do they focus on one idea at a time? Where do they need to fix their organization?