Yes there are more of these books and yes I'm still reading them. And loving them! After five books in the John Carter of Barsoom series Burroughs' plot lines had become somewhat formulaic. This 6th book breaks the formula a bit and introduces not only a different plot arch but an entirely different protagonist - Ulyssees Paxton, an American killed on the battlefield of World War I only to wake up on Mars.
Paxton finds himself in the custody of Ras Thavas, a mad scientist who runs a brain transplant laboratory. As is apt to happen to anyone who travels to Mars, Paxton falls in love with a beautiful Martian, unfortunately his love's brain is trapped inside of the evil queen's body that has stolen her beauty. It is here that that the tale plunges back into the familiar romance and adventure that is the signature of Burroughs.
There is an interesting subplot that satirizes both militant atheism and blind fundamentalism, adding another level to an already enjoyable read. If you are a fan of Barsoom you will want to read this.