As with all Theroux's travel books, this presents a somewhat idiosyncratic depiction of the country, enlivened by the people he meets and his extensive knowledge of literature about Mexico.
Theroux's elliptical style is not to everyone's taste. He tends to explore his perspectives as he travel and reads, often revisiting certain themes. This can be repetitive, at times, but I think it works in this case. Mexico is a large, complicated country -- 60 official languages, for example -- with really serious problems. This book is a heartfelt attempt to understand the people and their circumstances.
I skimmed a couple of longish sections about Mexican writers -- few of whom I've read -- and the emergent cult of Santa Muerte -- the saint of death -- too creepy for me. But other parts are fascinating -- visits to the US border towns, meetings with Zapatistas in Chiapas, being shaken down by the police. leading a writers workshop in Mexico City. Theroux was 75 when he began the trip, a testament to his vigour, courage and relentless curiosity.