This book is the second in the John Carter of Mars books. I haven't read Tarzan yet, but of the stuff I've read by Burroughs, the John Carter books are the best.
If anything, there is even less plot than before. The book takes only a few brief pages to get into its first sword fight and there after we move from sword fight to sword fight. Its the kind of book where you suddenly realize that the hero has been fighting completely naked for four chapters and that you had forgotten that fact.
John Carter is a kind of superman. Already having quasi-superhuman powers on Earth, on Mars he becomes super-human. Something that would later be reversed in the Superman comic strip. There is a huge influence here on things that were to come such as Howard's Conan, but Carter is the best.
This book is almost as good as the first. It obviously makes no sense at all at any point, but it is not meant too and any scruples about logic or the very many timely coincidences in the book are beside the point.
Interestingly, there is something of a message here. The plot is driven by Carter destroying the established religion of Mars, which is a fraud, inside a fraud, inside a fraud. All in all, it is quite a negative view of religion, and interestingly, considering when and where it was written, John Carter appears to have no religion of his own. There are many bits and pieces that look like they are subtle pokes at any organized religion, something that I found very surprising.
Burroughs is one of the greats of pulp writing and hopefully, people will come to see that good pulp writing can have a lot of merit. Well worth reading.