I think this is the first Jules Verne I've ever read. It was kind of laughably hilarious and completely improbable.
So, plotwise it does what it says on the tin. A German professor finds a 16th century manuscript with a 12th century note that tells you the entrance the centre of the earth. The Professor takes his nephew and an Icelandic guide to find the centre of the earth.
I think my favourite part of the book was when the professor was persuading his nephew that clearly the centre of the earth isn't hot and can't possibly have a liquid component. It's fine, they can totally just walk there.
So aside from the ridiculous science (including living dinasaurs, gigantic mushrooms, and a 12 foot person living entirely underground) the only irksome part was Axel, the nephew. He was basically a twat.
No wonder his uncle had to yell and boss him about all the time, he's clearly hopeless. He got dizzy going up a church steeple. If I was the uncle, I'd be like 'Okay Axel, you're clearly useless, you should probably stay up here'. He gets into all sorts of trouble and keeps getting dizzy or lost or just useless.
He was also really mean about Iceland!
...a little outside the pale of humanity; poor exiles relegated to this land of ice, who should properly have been Esquimaux, since they were condemned by nature to live on the edge of the Arctic circle. I tried in vain to catch a smile on their features. Sometimes they laughed by a sort of involuntary contraction of the muscles, but they never smiled.
The only woman in the book is Axel's love interest with the terrible name of Gräuben. Though Axel depicts her as smart, she depressingly says: No, dear Axel. I would gladly accompany you and your uncle, but a poor girl like me would only be an encumbrance.
So fails the test pretty hard this but you know, it's old. So whatever.
It's a pretty quick read and you spend most of the time laughing at the ridiculousness of it all. It's more fantastical than science fiction. Have a quick read if you want to see how far we've come.
I give it 3/5 starts for amusing.