I think the honest title of this movie should have been Reese Witherspoon Wants an Oscar. Really, she hits a lot of the clichés: she (at times) looks awful; she has many feels; she uses the f-word a lot; her character has had bad things happen to her and made awful choices; she gets a shot at redemption; she also Learns Things About Herself.
And sure enough, she was nominated! But, unfortunately, Julianne Moore was also nominated that year. And her character had Alzheimer's! Sorry, Reese.
Anyway: Reese plays "Cheryl Strayed", and she is hiking the Pacific Crest Trail, solo. She is initially out of shape and incompetent. Flashbacks show us how she got there: an abusive father, a dying mother, broken marriage, promiscuity, drug use, and an addiction to pretentious Simon and Garfunkel tunes.
The scenery along the way is fantastic, so there's that. And there's plenty of ways to get seriously killed or hurt on that kind of hike, and Cheryl discovers most of them, so there's suspense. Her project ran right up against the boundary between "noble quest" and "damn-foolish risk". Still, the movie kept me on her side.