There are apparently two editions for this book: one published with children in mind, and one with adults in mind. This is a children's edition, which means that there aren't any notes and the chapters are titled instead of numbered, with very obvious titles like "We Reach Iceland" and "Inside the Crater". You could read the list of chapters and get the whole story, really. It's also kept the original names of the characters - the narrator is Axel, not what was it, Henry? (Both are German names, but I guess Henry sounds more English!) This isn't an abridged edition, but there is an additional scene in the non-children's edition that I hear isn't authentic to Verne. Honestly, I was just happy to have this end.
In her introduction, Diana Wynne-Jones talks of reading and loving this book at the age of 10. As I was reading it, I kept thinking, ten? TEN?!? On the one hand, the loopy science and fantastical inner world would certainly appeal to children, though if I had read it at the age of ten I certainly would have questioned the science just as much as now; on the other hand, the descriptions are so hard to follow (because the writing is poor) and the story so often dull and slow, that I don't know that I would have ever finished it.
A great portion of the story is concerned with discovering the secret map in code, assembling a ridiculous list of supplies (that makes no logical sense, in terms of food and water - sorry, rum), getting to Iceland, and then traversing rock corridors within the volcano. And they never do reach the centre of the earth. Where they arrive at is a vast inner world, with its own sky and sea and cliffs and giant humans, giant sea monsters and weird colourless plants. And then suddenly they're on the surface again.
There's not much too it, and while Axel provides the foil to his eccentric scientist uncle, Professor Lidenbrock, he's one very annoying young man. The constant complaining (although he's often right - he says what we're thinking, much of the time) and whinging make him sound like a petulant little boy, and not much fun to be around either. I didn't like the Professor much at all either - he's completely lacking in charisma and can't listen to others. The real hero of the story is Hans, their Icelandic guide, who saves them time and time again, and without whom they would have perished before even making it inside the volcano. But don't worry, he got his pay! Dear me.
Overall, not one I'd recommend, though I hear Verne's other two famous books are better written.