Brilliant cinematography, no narrative
The point of a trailer is to intrigue the audience to look forward to watching your feature. In a way, you've succeeded on it. The backgrounds are stunning, the characters designs are appealing, and the animation, although limited, was admirable. However, trailers always give a brief summery of the story. Showing us the characters and what type of conflict they're in so we know if it's worth watching. Your trailer merely showed us random pictures in a sequence that I have trouble following. I've seen it three times and I still have no clue to what it is about. I give you a 5/5 for the good parts, and a 8/10 for the weak.