Lemony Snicket (or whatever his name is) accomplishes in A Series of Unfortunate Events what every writer ought to attempt—while maintaining traditional forms he expands and manipulates them to his own purposes. The result is wildly (really, wildly) entertaining fiction of the kind that will only become unpopular when good writing goes out of style.
Obviously these can be enjoyed by children. They're adventure stories, they're hilarious, they involve orphaned kiddos searching for clues to their parents' untimely demise (or was it a timely demise?), they're incredibly imaginative and involve things like a person so fat its gender cannot be determined, mushrooms that grow in the lungs and cause death within minutes, a baby who swordfights a vicious count, and signs made from chewing gum.
BUT this is only the Face Value (a phrase which here means only those elements which can be seen without looking beyond the surface). Snicket (a.k.a., Daniel Handler) crams so many literary and cultural references of the classic variety into each page of his sad saga that even the most attentive English major will miss a few. "Crams" is perhaps not the right word as it's never obnoxious or overwhelming—provides, maybe?
He's also incredibly witty, imaginative and simply a fine crafter of language. Some readers don't like the conclusion of the concluding volume; it is, however, one of the most consistent endings to any series, ever. That's all there is to say on that subject. If you're looking for things to be "wrapped up" in the traditional sense, you'd better find a different series.
And yes, the Baudelaire orphans have it bad. This really is A Series of Unfortunate Events, a series that becomes increasingly more unfortunate the longer it unravels. This isn't Snicket's podium for moralistic speeches—though the Baudelaires are children of character, their adventures escaping the evil Count Olaf are in fact simply more realistic portrayals of childhood than the sugary versions in other books.