Logan is the way the cinematic Wolverine saga had to end. It's gritty, dark, and sobering not just in the violence and language (it earns its R rating) but in the overall atmosphere. If you have seen the previews with Johnny Cash's cover of "Hurt" playing in the background, you have a pretty good idea of how the movie feels. The story doesn't end the same way the comic book arc does, but it is a movie that makes sense as the final installment in Wolverine's cinematic movieverse.
In the comics, Wolverine is something of a sacrificial lamb. He’s the best there is at what he does so others don't have to be. In more recent years he has looked at his past and thought, "Fate has put me through these things, so I know why I have to protect those in my charge." He eventually replaces Professor Xavier as both the physical and moral leader of the X-Men. He's the guy who has seen and done the worst things in humanity and has come through it.
Not so in the cinematic universe. Logan was never a hero in the grandest sense of the word. He was a monster channeled toward the good, a weapon of mass destruction aimed toward causes that were often just. There was always an edge to him – but that’s the appeal of the Wolverine, right? He wasn’t a tame wolverine. The instincts of the Law Of Tooth And Claw always coursed through his veins.
Xavier harnessed him; various women tamed him for a time; he had a soft spot for protecting vulnerable children. We occasionally glimpsed a tender soul buried beneath the muscle, hair and adamantium-bound bone. He was a guy you wanted on your side: he was durable and loyal; he didn’t mess around when there was a job to be done; he was willing to be the monster when he needed to be and sheathe his claws when he didn’t.
But he was always a monster. There were always demons lurking beneath the surface. "There's no living with a killing," Shane says in one scene. "There's no going back." Logan makes that reality very clear. The X-Men kept Wolverine in check; they certainly played a part in his his moral and relational formation. He was a better man for having sided with them, but he was always a monster.
In Logan, we see the real Logan re-emerge.