My Reaction in a Nutshell: 
 Well, this book fucked me up. 
 The Long Version: 
 First, I feel compelled to say that this book is 1,000 better than The Well of Ascension (TWOA). TWOA was more of book aimed at character development and dealing with the aftermath of Keliser's death. That book was about characters finding balance between who they were before overthrowing the Lord Ruler and who they need to be in order to run a kingdom. 
 The Hero of Ages (THOA) is about what happens after the gang realizes who they must become in order to be politicians and still claim some parts of their former selves (there still are some kinks and soul searching moments). There is more humor in this book and many attempts at trying to survive after Ruin was released in TWOA. 
 Taking place one year after the events of TWOA, Elend is Emperor and a mistborn with Vin close by his side. Readers get to see tragic backstories, Saze's depression, war, trickery, and more in THOA. Similarly to The Final Empire and TWOA, THOA also begins each chapter with a piece from an unknown text. These introductions to the chapters are longer than previous books, but they help things make so much sense. 
 Basically, I have way too many feelings about this book and am super close to spoiling it for everyone. The beginning was action packed, but there were some slow spots in the middle (to the point that I was worried that the pacing would return to what it was in TWOA) and quite a bit of summarizing too (to be honest, all the summarizing was a bit annoying). However, THOA had a rapid ending and the epilogue left me in tears. If you were on the fence about continuing the Mistborn trilogy due to TWOA, then I encourage you to leap off that fence like an Allomancer and dive into THOA. 
 Sanderson definitely redeemed himself with THOA. 
 ***TRIGGER WARNINGS: mentions of suicide/suicidal thoughts, war, house fire, burning people alive, earthquakes, tsunami, volcano erupts, death, murder