Right off the bat it's obvious the female lead Ellie/Grace Van Patten is a star and fits naturally in the role. She just doesn't look like she's acting, which is the whole point. She's perfect. I think I've met her before, well not really but it feels like it.
In complete contrast sits her male counterpart Danny/Callum Turner. Totally unbelievable: mannerisms, movements, speech patterns and accent. Comes across as he's forcing himself to act at everything. Didn't surprise me at all to learn he was born in England, as his voice slipped several times. Annoying.
The story is too drawn out. The dialogue is kind of dumb, overly simplistic, especially when it's trying to make points about the human condition, managing grief, and so on. The movie just isn't as smart as other reviewers seem to want it to be. I think that has to do with Ellie's performance. It's pretty much perfect. She needs help to make this thing work as a good movie, but never gets it.