Watamote strikes a harsh but beautiful chord on the harp that is its viewers. The show gives back what you bring to the table emotionally, which is both painful and uplifting. I would not go into Watamote expecting to leave satisfied and this is okay - it gives you as much as it can without compromising its identity. Ultimately, since the show is about you, I would glean what wisdom you can from it and let your own life be its happy ending.
Of course, Watamote is first and foremost a comedy! It sets up simple but satisfying jokes and executes perfectly. This is not a rushed or humor; bits are allowed to breathe and the viewer can usually feel the resolution coming long beforehand. One of the few animes I've seen that manages to be frequently laugh-out-loud funny, Watamote is very approachable from a western comedic perspective.
The OP is close to being great, but unfortunately it's not. Despite being visually perfect and starting off strong and rooted in metal, it quickly gets distracted, turning first to a more J-rock sound, giving us a 4-bar jazz interlude, flirting briefly with its darker roots, and eventually terminating in a truly cheesy melody and rhythm. If it had committed fully to the aesthetic that it portrays visually and in the first few bars, it would have been a fantastic OP. The ED holds up much better. It's a fairly typical Japanized electro-house tune, but it thrives in its simplicity and in the overlay of our desperate protagonists voice with the choir behind. This outro gets its message of acceptance across very well in an elegant juxtaposition with the theme of defiance given in the intro.