I absolutely adored this movie and I am only not giving it a perfect score because of the ambiguous ending. I had no trouble following the pace and flashing forward and backward in the character's mind. This may be a little confusing and irritating to some people though. The framing reminded me very much of the movie Closer. I think this movie Comet would best be suited for artistic, creative people and hopeless romantics.
I found the dialogue to be very real and I was on the edge of my seat the entire time. The two main characters have amazing chemistry together and I didn't even realize until someone else pointed it out in their review that they are pretty much the only people in the entire movie.
The scenery was absolutely beautiful and very inspiring. I think Kimberly was more wacky like Dell than she chose to believe. I think they were both very strange, offbeat characters and that is why they fit so well together but also why they tend to clash. The acting was absolutely amazing, definitely Justin Long's greatest performance.
I personally would like to believe in the optimistic ending which is that "being pregnant and not leaving Jack" is Kimberly's lie which she had never gotten to tell throughout their relationship. Dell had specifically told her the night that they met that she needed to choose the moment of her lie for a time when he was least expecting it and for when he was in A TRULY VULNERABLE STATE. So when he kisses her in the end and interrupts her, I think she was definitely about to tell him that was her lie and she finally fooled him. That is what I believe because I too do not want to live in a world where Kimberly and Dell do not end up together!