Disclaimer: spoilers ahead.
First of all, if you're coming here straight after season 1 then don't bother. I don't know why it's not stated anywhere on this page, but this highlights movie features half of season two, heavy with plot spoilers that should be avoided until you watch the second season. Which that out of the way, let's start.
Say in short, this is a highlights compilation that follows the two games against Aomine from season one and season two, and as we know, the games span multiple episodes and a movie format is just the perfect take on how to screen one of them. No commercial breaks in between, no constant interruption of the opening and ending theme songs, you just get the raw content ported directly from the TV show, bundled together in a seamless way that recaps you on one of the best games from the show.
I appreciate the original opening that came with this, the song was alright however the visuals were just stunning. You could tell from that alone that more effort went into this than simply piecing together recycled scenes.