What's not to like about Evil? I have personally always been a fan of the "dark side." I love Draco Malfoy, Cersei Lannister, and Loki. The bad guys are always so much more interesting than the good guys, in my opinion. So of course I was very excited to read this book.
The plot is great. Otto and his friends are invited to attend H.I.V.E. for six years, learning how to dominate the world. But instead of being thrilled at the opportunity, Otto and his friends decide that they want to escape from the school and return to their previous lives. Don't get me wrong - they're all about Evil, and they're very good at what they do. They just don't like being told what to do. (Fight the man, man.) So yes, it was fast paced and fun. And very clever, with all the references to Evil-doing. I very much enjoyed reading about their classes and homework. Walden included a lot of the standard villain tropes, which I enjoyed picking out.
What I did not find so great was the writing. This is the author's debut novel, and it really shows in my opinion. Some of the characters were very one-dimensional and stereotypical (like the fat Germany boy who said "Ja" all the freaking time). The book also jumped around to different points of view a lot. It would be one thing if every big break or chapter was about a different character, but I would often get different characters' perspectives within a paragraph or two of each other. It was a very jarring experience.
Overall, though, I found it to be just a fun read. While the book ended on a rather cliched cliffhanger, I will probably still read the rest of the series.