Just because I think he puts it really well, this is the verbatim post from Neil Gaiman's website:
When I first started writing comics for adults, I found myself forever needing to explain that, no, I wasn't writing those kind of adult stories.
The boundary between pornography and erotica is an ambiguous one, and it changes depending on where you're standing. For some, perhaps, it's a matter of whatever turns you on (my erotica, your pornography), for some the distinction occurs in class (i.e. erotica is pornography for rich people). Perhaps it's also something to do with the means of distribution – internet pornography is unquestionably porn, while an Edwardian publication, on creamy paper, bought by connoisseurs, part works bound into expensive volumes, must be erotica.
Alan Moore knows his words.
Moore has always championed underdog media: his work in superhero comics exemplifies this. That Watchmen was on Time Magazine's list of the greatest novels of the 20th Century is less surprising than its existence (it is a masterful superhero comic about time, mortality, age and nuclear fear, amongst other things) in the first place.
Almost ten years before Alan Moore's The League of Extraordinary Gentlemen, (a story that took many of the figures of Victorian popular fiction, including Alan Quatermain, Mr Hyde, the Invisible Man, and combined them in one huge romp), Moore, in collaboration with expat San Franciscan underground artist Melinda Gebbie, began Lost Girls, with a similar, although less fantastical, conceit – that the three women whose adventures in girlhood may have inspired respectively, Alice's Adventures In Wonderland, Peter Pan and Wendy, and The Wizard of Oz, now grown, meet in a Swiss hotel before the first World War. Wendy, Dorothy and Alice, three very different women, one jaded and old, one trapped in a frigid adulthood, one a spunky but innocent young American good-time girl, provide each other with the liberation they need, while also providing very different (and, needless to say, sexual) versions of the stories we associate with them – we go with the girls, in memory, down the Rabbit Hole, to Oz, and to Neverland.
Lost Girls began life, next to Moore's From Hell, in Steve Bissette's ground-breaking anthology Taboo. The first few chapters were collected by Kitchen Sink Press, but Kitchen Sink sank, and many readers wondered if Lost Girls would ever be completed. That it has been is cause, in the world of comics, for slightly disquieted celebration. Lost Girls is, after all, self-avowedly, pornography.
As an exercise in the formal bounds of pure comics, Lost Girls is remarkable, as good as anything Moore has done in his career. (One of my favourite moments: a husband and wife trapped in a frozen, loveless, sexless relationship, conduct a stiff conversation, laced with unconscious puns and wordplay, moving into positions that cause their shadows appear to copulate wildly, finding the physical passion that the people are denied.) In addition to being a master-class in comics technique, Lost Girls is also an education in Edwardian Smut – Gebbie and Moore pastiche the pornography of the period, taking in everything from The Oyster to the Venus and Tannhauser period work of Aubrey Beardsley.
It is one of the tropes of pure pornography that events are without consequence. No babies, no STDs, no trauma, no memories best left unexamined. Lost Girls, however, is all about consequences. It's also about more things than sex – war, music, love, lust, repression and time, to pick a handful of subjects (I could pick more). It's the kind of smut that would have no difficulty in demonstrating to an overzealous prosecutor that it has unquestionable artistic validity beyond its simple first amendment right to exist.
Melinda Gebbie was a strange and inspired choice as collaborator for Moore. She draws real people, with none of the exaggerated bodies of superhero comics or of the hyper-endowed people in the body of pornographic comics from Tom of Finland to Japanese Tentacle Porn. Gebbie's people, the women, and the men, have human bodies, drawn for the most part in gentle crayons.
Lost Girls is a bitter-sweet, beautiful, problematic, exhaustive, occasionally exhausting work. It succeeded for me wonderfully as a true graphic novel. If it failed for me, it was only as smut; the book, at least in large black and white photocopy form, was not a one-handed read. It was too heady, dense and strange to appreciate or to experience on a visceral level. (Your mileage may vary; porn is, after all, personal.)
That the material is problematic – no more so than many unillustrated novels, but then, it is, most definitely illustrated, and the -graphy part of pornography is what makes this a graphic novel – is obvious. Top Shelf has taken the traditional approach of a respectable publisher when faced with the problem of bringing out pornography, and has chosen to package it elegantly, expensively and beautifully, thus pricing, shaping, signaling and presenting it to the world, not as pornography, but as erotica. Whatever you call it, there has never been anything quite like this in the world before, and I find myself extraordinarily pleased that someone of Moore's ability actually has written that sort of comics for adults.