I've seen the short and it was truly great, so I went to see the feature-length version with great expectations. I was totally disappointed.
The first section is actually the short version, where the story of the 3 friends unfolds, but then the director focuses on 1 protagonist. I guess he might not be able to get the other 2 actors to 'complete' the story.
Shaun as the only one remaining acted quite well, but the story would've been much better if it explored deeper into his love-hate relationship with Vynn. The movie fell flat on several scenes because the director just couldn't build the story based on Shaun alone. He introduced 2 new characters but they really couldn't help much.
I guess Royston should've just left the short alone until he managed to build a stronger plot. All in all, 15 is a heart-warming short film, but a disappointing feature-length.