I've always been blown away by Palpatine's master manipulation skills, so it was cool to peer behind the curtain and see how he managed to manufacture a war for his own gain. Plagueis is an interesting character, and I liked his philosophizing on Sith principles - and how his arrogance was ultimately his downfall. 

Lots and lots of galatic politics and economics, though. That aspect really made my head spin at times. Also, I constantly had to look up the species being described because I haven't read a ton of Star Wars books, so matching the names of the species to the visuals I know from the TV shows and movies was a bit harrowing at times.