This was probably a lost war from the beginning. I think we did about as well as could be expected, but ultimately Sanderson taking over just didn't land.
I think the biggest issue is that Sanderson's characters seem too similar. It's as if they are all siblings, with identical worldviews and internal voices. This was quite frustrating to me, as the characters are still defined by their actions, but on the inside it seems like they are all the same soul with different shells. Sanderson seems to focus on action and events over characters. This is fine if the entire series is setup in this way, but Wheel of Time was not an action heavy series, it was a series of characters.
Jordan spent an inordinate amount of his prose on sidequests, character interactions, setup, deliberation, travel, etc. Despite this, I enjoyed his writing. I liked that this was an epic story, but it was really just about characters. I sometimes enjoyed even hearing about the banal parts of their lives, the same way you enjoy hearing about the boring day of someone you care for. The whole series was more about loving the characters than it was about what was actually going on. I think Jordan (even more than his readers) loved his characters too much, to the point of favoring indulging in writing them over actually moving the story forward.
I think Jordan failed to setup a "high action" foundation, but I don't think action was really the point of his Wheel of Time. Book after book, Jordan kept inflating this balloon of plots, not even beginning to actually release the pressure until basically book 11. This made Sanderson's job of "deflating" the series even more difficult. With Sanderson suddenly attempting to actually close things out, things felt rushed and sometimes even tacked on. Sanderson didn't just have to finish another author's work, he had to simultaneously change the focus of that work from indulgent characterization to action and plot progression.
Maybe I'm just bitching because an author that I really enjoyed died. What were the alternatives? Sanderson did all he could to close the myriad open threads, to raise the amount of actual action in the series, to find his own footing when taking over a work he didn't start. He took over a series about people and made it one about plot, it is good, but it isn't Jordan's Wheel of Time.