Sensei asked our opinion about what makes a good blog. "Your comments will serve as a guideline for you at the end of the semester when your own blogs and those of your classmates’ will be evaluated."
A good blog for me would be well-written and interesting -- good style and good content. But these are such subjective qualities that I don't think they should serve as criteria for evaluation.
I find sensei's question difficult, in part because I don't keep my own blog or read other people's personal blogs (so far). None of my close friends keeps a blog. The blogs I read are professional or impersonal, like the Wall Street Journal's blogs on various topics or Arts & Letters Daily, which is a collection of links to articles that a few academics find interesting. (AL Daily has inspired certain posts, where I just link to things I've enjoyed reading or seeing.) But the qualities of these blogs seem relatively inapplicable to our personal blogs for Japanese class.
I think the criteria for evaluation should reflect the purpose and guidelines of the blog. Such as (pasting from the Class Blog Page):
"You can write about anything (well, as long as it's legal), for example, activities you do after class, what you would like to do in Japanese, and even suggestions/complaints about our Japanese class."
"Expressing your thoughts, feelings, opinions etc. to others (me, classmates, Japanese students in other schools, Japanese-speaking people) in Japanese and/or other languages of your choice)."
"Remember, you are encouraged to express yourself about any topics in any language."
So, I'd say that a good blog, for evaluation purposes, is one that tries in good faith to meet these criteria.