This is not really a review but rather a description of what is found within the story. It is written primarily for those who want to know the details and who don't care to spend $7-10 on the e-book. So this is more of a summary than anything else. You have been warned.
This short story, which is found in the anthology Unfettered, was about 12 Nook pages on my iPad (in reality, those "pages" were nearly 2 iPad screen pages each). It is the story of Bao's final test to prove that he is the prophesied Wyld, meant to free the Sharan people from the trammels of time and to protect them from the destruction of the Dragon. There are hints of Bao's two years in Shara, from his arrival as a slave to his leading of a successful revolt in the aftermath of the disappearance of the twin monarchs and his winning over of the Ayyad.
"River of Souls" is told from Bao's point of view and in it, he reveals a conflict between various duties and his believed need to deny the warmth of certain passions. As he crosses a huge rent and a rivulet known as the River of Souls (from whence the Wyld shall draw his first drink after being "reborn" in order to enter a ruined temple to face an unknown guardian, there are certain background features of Shara given in a cursory fashion.
The temple scene involves Bao confronting a fully-grown jumara and a full description of this shadowspawn is given. There is also a mysterious blooming within, with the secondary guardian, who awaits his (desired) death, being a Nym. The quest object is a cup, which Bao affixes to a scepter that he had already tracked down.
As a story, "River of Souls" will hold only a few points of interest for WoT fans. It is a simple tale, with little in the way of imaginative prose or thrilling dialogue. Yet it works to fill in Demandred's backstory in a way that it wouldn't have if it had been included in A Memory of Light. Can't say that it is a "great" story, but it certainly is a tale that hints at a deeper backstory that would have had the potential to be a decent book or mini-series of books. Perhaps that is all that some would want and for those, "River of Souls" would make for a short, pleasant read.
Pitty that the shara were mislead and that we don't get more of that area. I always thought it was interesting and there was an interesting story to tell there.