I love Flint. I know that it's corny and the end is kind of silly, but I don't care very much. This is partly because it's a nostalgia read for me. L'Amour was probably the first writer I ever loved. When I was 13 and 14 years old I read my dad's old L'Amour paperbacks one right after another. It didn't matter to me that they were formulaic with the same kinds of characters and the same kinds of things happening in every single one. They had fast plots and lots of action, and I enjoyed the western settings (of course, I also liked L'Amour's non western novels, like Last of the Breed, The Walking Drum, and The Haunted Mesa). It turns out I still do enjoy all those things.
The novel is about Flint, a mystery man who was found as a child by a burned out wagon train and then handed off, unloved, from one poor farmer to another until, abandoned for the last time in a tiny western town, he was found by an old gun for hire who paid to put him in a boarding school for a few years before educating him in the art of surviving the rigors of the old west. When the gunslinger is murdered, Flint, well trained and something of a gunslinger prodigy, takes immediate dramatic, and violent revenge before disappearing from the west and becoming the legendary "Kid at the Crossing."
When the novel begins, Flint is older, he has become a hugely successful New York businessman (this is unfortunate for L'Amour, who is unconvincing and at his worst when describing Flint's various financial moves), but he has cancer, his wife has tried to have him murdered, and he has moved back West to die in a remote and peaceful oasis in the Malpais desert. His plans to die in peace are upended when he gets sucked into a brutal range war. His enemies don't realize they are up against the legendary Kid at the Crossing, and that he has nothing left to lose.
I mean, this is all you want in a Western!
SPOILER ALERT: Ok, what I'm about to say next is definitely a spoiler, but I have to mention it because it's the most ridiculous part of the book. The main thing about Flint is that he's dying. This fact influences everything he does, and L'Amour frequently waxes poetic about Flint's immanent death. So, when, at the end of the book it turns out that Flint is NOT going to die and he was misdiagnosed, the reader definitely feels like L'Amour has pulled a fast one. We are happy about it because we want Flint to be happy, but it also makes everything that went before seem kind of silly. It feels like L'Amour cheated a bit to give us a happy ending.