Well, in the words of Rustin Parr, I'm finally finished.
I'm going to give you as bare-bones and spoiler-free of a review as I can possibly manage. I'll be able to manage it pretty well, too, although there is one major plot point that, frankly, it's kind of nuts for me NOT to talk about. But since it's been absent from the book's marketing, I'll leave it for you to find out on your own; seems like the right thing to do.
I ingested The Outsider -- which spans 561 pages -- in a mere two days, and that right there ought to tell you something about the novel. That's a big chunk of reading and not a long span of time in which it was accomplished. So was it compulsively readable? You better believe it.
Unfortunately, that's not enough for me to give the novel anything more than a weak recommendation. Allow me to explain.