It impressed me so much I put off reviewing it til I was certain I could do it justice.
I ... actually have no complaints with this book? I found it stylistically irreproachable, beautifully written, and quite gripping too. Each time I picked it up, I found I flew through it until life forced me to put it down. Eleanor Oliphant balances hilarious, relatable moments with heartbreaking ones; companionship with crushing loneliness; and the eponymous main character is so /odd/ and loveable, she really shone. I want her to be real so I can hug her. She FELT real.
The themes are perfectly handled, too. There are two aspects of this which impressed me so much that it made the book a favorite:
1. - Eleanor battles depression and yet /this isn't one of those ✨depression aesthetix✨ books/. In fact, she gets help and support, (and, thank HEAVENS the therapist is not demonized because Nobody Understands Me™ - a tired and harmful trope I keep seeing). Her battle with mental illness isn't the main theme of the book (hooray, I think we've all had enough suffering porn in our literature); rather, it's treated, well, just like any other illness. She gets off work, she sees a specialist, her friend checks up on her and brings her food and nice things - it made me so emotional. Books like Eleanor Oliphant help normalize and humanize mental illness in a society that often treats it as taboo. 
2. - The book focuses on Eleanor's personal growth and the way she views the world - and the author didn't give her a romantic partner to Show Her The Meaning Of Life (OR, God forbid Cure Her Depression). Let's hear it for fiction that DOESN'T focus on romance. Her friend Raymond helps her, and it's so sweet and he's such a good person and PLEASE CAN WE HAVE MORE BOOKS IN WHICH FRIENDSHIPS ARE SEEN AS EQUALLY SPECIAL AND FULFILLING TO ROMANTIC RELATIONSHIPS??
In short, we need more books like Eleanor Oliphant Is Completely Fine. A shining example that several contemporary authors would do well to learn from!