Tunneller40's review is spot-on. Writing about caves is difficult, and Tabor does a pretty good job. But first, the not-so good stuff: technical errors - carbide lamps have jets, not wicks, for example; purple passages - a "bottomless" sump, for example; and absurd digressions, such as this on the subject of underground dehydration: "It is not too great a stretch to visualise thirst-crazed city dwellers drinking their neighbours' blood..."
Eh?
Still, Tabor's story is by a non-specialist, for non-specialists, and it captures much of the excitement of intense caving. The description of the six-day trip by Bill Stone and Barbara am Ende to the bottom of Huautla is genuinely thrilling. I recall sitting at the top of a pitch in a deep Pyrenean pothole after 20 hours on the go, hallucinating and hypothermic (but fortunately well clipped on) - and on that occasion I had only been underground for three days. Six days, on the wrong side of a big sump, at great depth is unimaginable.
As has been said, Tabor concentrates unnecessarily on an implicit duel between two very different expedition leaders. The caving expeditions I used to go on never had 'leaders'; they were loose cooperatives, with everything done by consensus and trust, and they worked fine that way. Harder to write about, though.