On the surface, Erewhon is a somewhat less humorous Gulliver's Travels meets a less righteous Shangri La, a dystopian "hidden civilization" story satirising much of the Victorian society Butler lived in, and despised.
But it is so, so much more than that. Unfortunately the real gem here, is hidden near the end of the book, and I think a lot of people simply don't make it that far, swamped as they are by the heavy victorian stylings, the near total lack of a narrative, and the tendency for Butler to wander off into very strange and winding tangents. Personally I found some of the prose hilarious, albeit unintentionally, and that the framing story, indeed the entire plot such as it is, is more or less irrelevant.
I present for your enjoyment:
"Oh, wonderful! wonderful! so lonely and so solemn, with the sad grey clouds above, and no sound save a lost lamb bleating upon the mountain side, as though its little heart were breaking. Then there comes some lean and withered old ewe, with deep gruff voice and unlovely aspect, trotting back from the seductive pasture; now she examines this gully, and now that, and now she stands listening with uplifted head, that she may hear the distant wailing and obey it. Aha! they see, and rush towards each other. Alas! they are both mistaken; the ewe is not the lamb’s ewe, they are neither kin nor kind to one another, and part in coldness."
But this is the book that inspired the Butlerian Jihad, the destruction of computers and the creation of Mentats, that lies at the very heart of Dune. This is the book that first raises the idea of Artificial Intelligence, machine conciousness and applies the theory of evolution to machines. In the 1860's! The theory of evolution was barely being applied to animals yet, and here's Butler predicting that eventually machinery would evolve faster than humanity and take over, nearly a century before Turing and Asimov. This segment of the book, in fact the first one published, originally as a New Zealand newspaper article "Darwin Among the Machines" is a rather stunning piece of speculative fiction, long before the term existed. Even if you can't manage the rest of the book, that chapter is well worth reading if you have any interest in sci-fi at all.
Overall I find the book quite hilarious, and rather more fun than Gulliver (sorry, that's an eternal DNF for me, I've read the whole thing, it's true, but never all at once). This is a subtle self-deprecating humour, starting with the second preface to the second edition, where Butler writes of the first edition:
"I made a few unimportant alterations and additions, and added a Preface, of which I cannot say that I am particularly proud, but an inexperienced writer with a head somewhat turned by unexpected success is not to be trusted with a preface."
And he is not unaware of the fact that he is a bit of a rambler, at one point excising a section of his "translations" of the holy books of Erewhon with
"Here the writer became again so hopelessly obscure that I was obliged to miss several pages."
Plotwise, there's nothing terribly much here: A young man is working in an unnamed country, well understood to be New Zealand, some editions even carry a Butler drawn map showing roughly where in Canterbury Erewhon lies. Deciding to seek his own fortune, and looking for some arable land he can stake a claim to as a farmer, he goes wandering over the mountains and stumbles into the unknown country of Erewhon, which is remarkably like England, except for where it's not. Here, being ill or having a poor constitution will get you sent to prison, whereas being all overcome with an attack of immorality or embezzlement will pass just as soon as you get treatment. Here, banking is a religion, and unreason and hypotheticality are the peak of academia. And Butler uses this unlikely situation to point out the irrationality of his own society: How punishing someone for having a poor constitution is just as ridiculous as punishing them for having had a rough upbringing is back home, for instance. There's some very pointed quotes:
"It is not our business,” he said, “to help students to think for themselves. Surely this is the very last thing which one who wishes them well should encourage them to do. Our duty is to ensure that they shall think as we do, or at any rate, as we hold it expedient to say we do.” In some respects, however, he was thought to hold somewhat radical opinions, for he was President of the Society for the Suppression of Useless Knowledge, and for the Completer Obliteration of the Past."
In the end, it's a difficult book. I enjoyed the first couple of chapters, in all honesty, more than I ought have, the description of early white settlement in NZ, of the daily life of a sheep station, of the shearing shed and the happenings in one, are vivid. A lot of my childhood was spent on such a station, and the life Butler describes is not much different from that of a hundred years later. I suspect most people would gloss those first chapters. The actual adventure of finding Erewhon, and most of the happenings there, are dull, and while some of the satirical treatments still hit the mark today, some of them miss by a mile, or perhaps I am too far removed to understand their targets. Bear in mind this is a book typical of it's day, with random passages in French and Latin - and an explanation why a chiding from a reader that "any fourth form boy could do better" resulted in a correction to the Latin. How times have changed. There are references to random greek classics, quotes from poets and playwrights, and, well, it's a lot of work to read the entire thing.
Give this a shot if you're interested. If you like Victoriana, as a whole, you may find the style charming. But I suspect most modern readers would get the greatest value from the chapters near the end, on the rise of the machines, because they are by far the best part. 4 stars just for that bit.