I agree the story is reasonably entertaining. The plot wasn't all that surprising, but was still interesting enough. The worldbuilding is coming close to the Erikson levels of breadth-over-depth, but it is still okay and reasonably interesting.
But all these are buried under pedestrian character and thematic development. The handling of Shallan's family was decent, but Shallan herself is held back by his inability to write "witty" dialogue. If he'd just taken that element out, it would be better, but he insists on overwhelming the reader with instances of her being witty, and it just doesn't work. Also, by making her a person who simply buries and refuses to acknowledge catastrophic incidents in her life, he's made her a lot less interesting as a person.
Kaladin was just bad, this book around. To develop to theme that he needs to help and protect even people he hates (why, though? Why is it okay for him to fight and kill Szeth, who he doesn't like? Who not protect him too? Why won't this be an issue when he's fighting Voidbringers? It makes no sense), Sanderson goes through a plot where he's complicit in a planned assassination of the King. Then, he's made to realize that the King is just like his brother who also tried, but was sacrificed because he just wasn't good enough.
How is this done? By the King revealing to Kaladin that he is indeed trying just a couple of scenes before Kaladin has to make his choice. There's no build-up, despite the fact that Kaladin has been guarding the King for weeks at least, and would have had to see him trying if he truly was.
And what of the larger point? Sure, an assassination may not be the best way to deal with an incompetent king. But just because he's trying doesn't change the fact that loads of people are dying because of his decisions. But somehow, deciding to not assassinate the Kind ends up being keeping the King on his throne and supporting him fully.
Sanderson has failed to put in work on things that are really critical to making a successful story. Themes and characters are merely props to show off awesome battles and 20 different magic systems, rather than things being the other way around. This happens in other epic fantasy series too, but that this is already an issue in book 2 of the Stormlight Archives is troubling.
In a ten book series, mere plot twists and world building isn't going to be enough to hold my attention. I need something more, and I just don't see it right now. At the current rate, I see myself washing my hands off the series by book 3 or 4.