I was looking forward to this, now I can see the only problem with it, which is the outline, allow me to elaborate:
When you create the image on a computer(vector) you make a pretty good job at the time of re-drawing it, as you just demonstrated it looks a like a pretty clean vector. But as I have noticed, this drawing contains heavy usage of black and dark colours, when this sort of colour range is used, the best option to contrast the different elements is to use a subtle outline to differentiate the different elements, in this case the best option is to use a different colour outline(Which can be a Gray-ish outline instead of a black one for the ponies), this same technique can also be used to contrast different elements in the background such as the mountains and the grass(in the case of the last two, a thinner outline can be used to give some contrast to the background objects like the mountains and the skyline).
Apart from that, its a pretty nice job, specially with the lighting effects which look pretty clean, the vector itself and the outline width seems pretty correct and looks really cool overall, specially with the renewed sky which really gives it a sort of "spirit" to it, I don't know how to described correctly on English but integrates the elements quite nicely.