Some of the things writers say about essays remind me of the traits of blogs; some of the things writers say about blogs remind me of the traits of essays. I'll gather some quotations here to start to explore that. Maybe others will come to your mind, too?
Like you, an essayist struggles with the here and now, the world we have, with sore and smelly feet and humiliation, a freethinker but not especially rich or pretty, and quite earthbound, though at his post. (xix)
And the form of composition Montaigne gave a name to would not have lasted so long if it were not succinct, diverse, and supple, able to welcome ideas that are ahead of or behind the blurring spokes of their own time....[The essaysist] is an advocate for civilization.... Working in the present tense, with common sense as his currency, "This is what I think," he tells the rest of us. (xiv-xv)
[Essayists] are not nihilists as a rule. They look for context. They feel out traction. They have a stake in society's survival, breaking into the plot line of an anecdote to register a reservation about somebody's behavior, for instance, in a manner most fiction writers would eschew, because an essayist's opinions are central, part of the very protein that he gives us.... He has the job of finding coherence in the world. (xvii)
[The] essay's innermost formal law is heresy. Through violations of the orthodoxy of thought, something in the object becomes visible which it is orthodoxy's secret and objective aim to keep invisible. (23)
The law of the innermost form of the essay is heresy. By transgressing the orthodoxy of thought, something becomes visible in the object which it is orthodoxy's secret purpose to keep invisible. (171)
On the other hand, there are the feeble imitations of the real thing. Austrian writer Karl Kraus said that certain would-be essayists were merely "baking bread from bread crumbs." I like Kraus's provocation there. No doubt there's more to think and say about the weaknesses of both genres.