Sasuke's role in the movie was the same as in the manga, mixed with that of Itachi; Sasuke helped the protagonists from the shadows like Itachi, but did it seemingly on a whim like his usual character. In other words, despite probably being shown in the movie for a combined time of about 1 minute, he saved the village from destruction, saved EVERYONE on the moon by bringing back the catalyst that would buy them another hour before the raikage blows it up (Hiashi), and subtly chided Kakashi's lack of power in the face of stopping disaster to the village. That is time well spent in my opinion.
The movie is legitimately part of the overall manga plot, though highly focused on Naruto and Hinata's relationship.
