If you're after a longer story, especially compared to the shorter novels they're pumping out for Star Wars these days, then this could be for you. Especially if you want something that delves into Sith lore and philosophy. It's a little misleading to call the novel 'Plagueis'. Yes it's about him, sure. But it's also very much about Palpatine. And Republic politics, and how private enterprise fits in with Republic society.
Also, as a fan of the Old Republic era, this novel ties in both that era and the current one quite nicely. Too bad it's relegated to Legends status now, as is all the Old Republic material. Shame.