Ok, Positives:
The art style is good. The animation for the most part is good for what it is.
Negatives:
First off, as you said in the description, the audio seemed very grainy and subdued, like it had been recorded using a camcorder or phone from being played somewhere else. Thematically, the music fit, but the pacing was off so it really made it stand out.When it comes to trailers, the music synching with the visual queues is almost as important as what's being shown on screen. The pacing seemed to be picking up as the city panned, leading to some dramatic moment and then... peaceful view of a train going through the city. The purpose of a trailer is to get people interested in your final product and the best way to do that is to punctuate several dramatic shots in conjunction with dramatic points in the audio track that runs with your trailer.
I think you've got some talent and I'll look forward to seeing your final product when it arrives.