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. The book shows the true magnificence of his manipulations. It is revealed he killed his own parents and siblings, and is incapable of feeling regret when committing heinous actions and various misdemeanors—such as when he ended up crashing his landspeeder and killing two people without any remorse on his part, and, in fact, was extremely glad that he got away with breaking the law and insensitively decided to reveal that instant that he wants to become a racer. In addition, when Darth Tenebrous, a Sith Lord, foresaw Palpatine's murder of Plagueis upon his death and possession of Plagueis after the latter betrayed him, he was noticeably horrified at not only Plagueis's murder at the hands of Palpatine, but at how evil Palpatine is, implying that Palpatine was so evil, that even the Sith, who are infamous for committing various crimes with The Dark Side, were repulsed by him. he engineered the invasion and blockade of his own home planet (using the sympathy generated to become Supreme Chancellor and eventually Emperor)
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 by killing all his family 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.