I must point out something first.
In Scalzi's earlier book, The Kaiju Preservation Society, we have Jamie Gray, who in the opening pages of the book loses his unremunerative job as a food delivery courier and then gets dragged into a mysterious international organization that is doing things that are pretty unbelievable.
In Starter Villain, we have Charlie Fitzer, who in the opening pages of the book loses his home and is spirited away from his unremunerative career as a substitute teacher to get dragged into a mysterious international organization that is doing things that are pretty unbelievable.
Just sayin'.
Now, there really are differences. Jamie is a mouthy asshole but actually turns out to be pretty brave and competent as an action hero. Charlie is meek and almost milquetoast but stubborn and loyal - and also actually pretty brave. Where Jamie was dragged into a very sci-fi scenario involving preserving magical megafauna on a planet that's apparently in another dimension, Charlie is dragged into a merely James Bondian scenario involving a secret cabal of obnoxious supervillains, with whom his recently deceased uncle was somehow involved.
Oh, and also "talking" cats - although they have to use specially modified keyboards to communicate. If this reminds anyone of science fiction author Mary Robinette Kowal's cat Elsie, it's not by accident, as the author notes in an afterword.
This was a moderately entertaining book, but not a great one.
( Cut for more, including additional snarky remarks and some spoilers )The awful thing about this is that I like Scalzi as a human being. He has done a number of very good things for science fiction and its fandom, and he is IMO one of the wittiest people on Earth with a tweet (or whatever they're being called these days). But this is not his best effort. I might have been able to ignore that if this book hadn't been shortlisted for the Hugo Award for Best Novel.