I think more recent Brandon books feel less well revised than other ones, maybe because he has more pressure to publish things now? Especially with the secret projects, there was not a ton of time to revise them, and he was trying to write Stormlight 5 at the same time.
I also didn't feel too much emotional connection with Sigzil. Throughout the story, his character seemed to change a lot. He didn't seem consistent, and the only real emotion that I got from him was exhaustion. When Aux died there was no grief. I was sad, because I liked Aux. But Sigzil didn't seem sad, and I didn't feel sad for him.
That being said, I really liked this book. Even though I didn't connect with Sigzil very much, there were moment (like the bridge four salute) that were awesome, and the book worked really well anyways. It wasn't as character focused, or at least, it only focused on one character who wasn't that good, but I still enjoyed it more than any other Brandon stand-alone. I hope that maybe seeing Sigzil in Stormlight and having a better explanation as to what happened with him might help to re-contextualise the book and make it a more enjoyable read, but I find it unlikely since Sigzil really isn't the focus of Stormlight.