A very interesting story and one that indeed does turn out to be better than the other ones by Burroughs that I have read and I am a fan of Burroughs. To get it out of the way, as one would expect for a pulp novel set in Africa written before the outbreak of World War I, there is lots of racism however a reasonable reader can hopefully look beyond this and see the great merits of the book. It has a great story arc, ending on a cliff hanger, which is standard for Burroughs. It is structured very well and has only a fight scene once every ten to twenty pages which is restrained for Burroughs.
It is the character of Tarzan, himself that makes the book. Burroughs explicitly considers him an ideal man. He is not, however, treated as a normal noble savage, but instead is depicted as a Wild Beast who implicitly contains the instinct of the English gentleman and the wild beast and is distinguished by a greater degree of savagery and by reason from the beasts of the jungle. It's an original and compelling, even startling and unsettling ideal which has never been remotely captured by any of the adaptations I've seen.
Interestingly the first third or so, is quite reminiscent of the Mowgli sections of the Jungle Book.
Overall, very good and confirms my belief that Burroughs was one of the true masters of Pulp fiction.