Currently re-reading this series, on book 12 at the moment.
Always thought that the books would be a fairly easy adaptation to a TV series because of the excessive description of details (starts going crazy with them around book 8 which 1/3rd of the book could be used to create a season for Project Runway with all the dress descriptions). But, the details are so precise that the story boards for the director are already in the books.
Characters in the book are described in detail, not just once, but in every book as Robert apparently wrote like he thought his audience has dementia and forgot how characters looked, what they did and what they were between books. He also detailed the differences between characters when they interacted. In the image of them walking from the TV show, Perrin is half a head taller than Rand, in the books when they meet, Perrin is immediately described as half a head shorter than Rand.
Aes Sedai are described as "ageless", but descriptions in the books make them sound like they are stuck in their twenties as they reach the tower usually in early/late teens and starts getting the ageless look once they start using the power more and more.
Cast so far
What I think will make or break the show will be the "magic". Unlike GoT, every book has basically an end showdown with magic/power. And not just some of it, but major battles where it is the defining part of it. Same with the creatures and their abilities. Taking a golem and making it fit to a crack in a door, or the warder cloaks, mythradaals...
GOT large action scene: "Battle and dragon swoops in shooting fire at some stationary targets, some targets/people burn, ice wraith throws ice spear, dragon falls down" Think that was the most magicy of the battles that required the most CGI?
One example of a WOT battle: "Summon armies of heroes using magic charging in on magic fog to fight armies using magic against eachother while a man fights an apparent flaming wizard in the sky using magic and flaming swords".
They need a full feature Marvel level CGI treatment which would skyrocket the cost of battle episodes beyond the GOT ones. Which I don't think they will do. Which is why I think they will tone down the fights/actions. Which is why I think it will be bad overall.
Done right, it could be a really cool series. I don't think they will do it right.