These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Some thought this book would humanize Palpatine by showing his origins; Instead, it turns out he's been an amoral sociopath from the beginning.
Fridge Brilliance / Fridge Horror: In Episode III Palpatine says that "[Plagueis] had such a knowledge of the Dark Side, he could even save the ones he cared about... from dying". Now wait a second, just whom could a Sith Lord ever actually care about? Oh, his test subjects...
Though, considering he was willing to destroy a Sith tradition just share the universe with what he saw as a son, maybe the guy just loved easily.
Magnificent Bastard: Darth Sidious, whose magnificence here lays the framework for his schemes throughout the saga.
Moral Event Horizon: Palpatine crosses this fairly early on and takes up permanent residence beyond its border.
Reread Bonus: Seriously, if you read this book once, it's awesome. If you read it again, you'll come to realize just how manipulative Sidious is.