I'll just name a couple of things I've been told right off the bat. First thing is the shadows. I don't know if they look realistic, but I hope (yes I tried to fix them as per your suggestion, Mackaged).
Another thing I was told is that the picture looks too dark and gloomy for their expressions. This was supposed to be kind of like a scene after the battle with Nightmare Moon, however, I didn't realize until after that the sun was rising after the battle in the episode. I guess this could be considered an alternate ending of sorts in that case. I don't know, I guess you can take it as you will. I wanted to scrap this after I found that out, but I just put way too much work into it. After about five hours of work and 45 layers, scrapping it would have been pretty deflating.
As for the title, well, this was the day they were "destined" to come together to defeat Nightmare Moon, though I realize the title may be cliche so I uploaded a textless version as well.
Textless version can be downloaded here: [link]
Vector of the Mane 6 made by: ~Ryoki-Fureaokibi
Background vector made by: ~EmberFiremane
Surprise Luna vector made by: ~Pustulioooooo