I cried multiple times. That's never happened to me before while watching a TV show. This anime portrays characters with more emotional depth, realism, and accurate relationships than any live action show I've seen. None of the characters are cardboard cutouts where a character should be like in so many other anime, even the ones that seem like they have no depth at first are fully realized by the end.
Many criticize the latter episodes as being poorly executed and taking the story in a different direction, I found them to be decent and tie things up nicely. The anime is a self contained story with a beginning middle and end, and while I wish the latter episodes had been made into a full season to flesh out the plot and allow time to digest the twists that happen, I have no serious criticisms other than certain latter plot points being rushed, and a few things that happen throughout the show being vague or slightly redundant.
The action is pretty good, above average but serves as more of a backdrop to allow further development of the characters, don't expect the best mecha fight scenes of all time.
I can't recommend this enough, it's one of those anime that transcends romance and mecha anime, and anime as a genre itself. Easily one of my favorites and I'm very picky about anime. 9/10