It is hard to find much information on how they sore it. Best I've seen for a little bit of insight are at the links below. Seems that each essay question is scored by at least 2 people. They use a method called Partial Compensatory Scoring to allow you to make up some mistakes in the...
Took both for the first time this weekend. Challenging for sure. I felt the lateral was a bit harder than the NCEES practice exam. Vertical was inline with what I was expecting.