Two high quality seasons do the series justice, with a third as of now currently in the making. Generally, the way the series progresses is through a mostly episodic format. Each season would start by introducing characters, engaging them in comedic situations, and later expanding upon the story in detail. The only problem with this format is that it is initially misleading for those who want to judge the series immediately upon watching a single episode, but as a whole the series is able to offer incredibly well-rounded entertainment as a result.
Now one of the fundamental problems with this movie is the episodic nature of mixed comedy and drama lends itself to awkward execution for a standalone production that is meant to run for over 90 minutes. Sora no Otoshimono does not have a plot that is told continuously from start to end. There are breaks in between action due to the comedic nature of the series, and story arcs are fairly brief. The brief nature of these story arcs isn't necessarily a bad thing, but for this movie it creates a situation where a lot of time is wasted simply trying to overextend the plot so that it fits in a 90 minute time window.
The first 40 minutes of the movie go into the introduction of Hiyori Kazane, a character who was briefly seen late into the second season of the series. Through flashbacks and reused footage of the previous two seasons, we see from her perspective how she has held constant romantic interest in Tomoki. Understandably, this recap of previous events is somewhat helpful for viewers who have not seen the first two seasons. However, it also comes off as redundant as in each flashback from different episodes over the course of 40 minutes, essentially the same thing happens. While Tomoki and his friends are up to some shenanigans, Hiyori is watching from the sidelines, narrating how she wants to have fun with Tomoki, but is scared to say anything to Tomoki or much less look him in the eye.
As the character of focus in this movie, Hiyori proves to be a rather uninteresting character. She can be summed up as being a bad case of Yamato Nadeshiko, or in other words an ideal, soft spoken, and submissive Japanese woman. If there is anything entertaining about this personality, Hiyori's naivety around Tomoki's perverted schemes comes off as comedic, but as a character she exhibits very little development or enlightenment to strengthen any interest in her.
The movie does have some good things going for it in spite of its glaring fundamental problems. The best part about this movie is that like the seasons before it, it maintains high production quality. Animation for this show is top notch especially during the few high action scenes. Voice acting for each of the familiar characters is appropriately executed. And even though Hiyori exhibits poor characterization and development, Hikasa Youko, who is probably known better for many strong-willed female roles, does an excellent job delivering her soft-spoken nature.
All in all, Sora no Otoshimono, or at least the part of the story in this series that was chosen I do not feel lends itself to being able to support a full feature length movie by design. While the series maintains a solid story, it does so in bits and pieces with comedy scattered in between, and it is not set up to normally maintain an extended plot arc. As such, most of the movie watching experience may feel largely like a waste of time when half the length of the feature is occupied by flashbacks involving reused footage with commentary from Hiyori. This production in this way fails to maintain what made the seasons before it so entertaining, by losing the ability to jump and flow readily from comedy to drama to maintain viewer interest. The level of freshness and energy that the TV series could maintain for episode duration simply could not be accomplished for this movie.
To be fair, the execution problems the movie has are not uncommon for a lot of movie adaptations for other popular series, due to the nature of movies picking up at a place somewhere in the middle of the story. If you can accept that in your viewing experience, you can at least appreciate that this movie does have amazing production quality to redeem itself.
