Nice work for your first piece of film making.
You had some really nice imagery there. Some of the shots were pretty cool.
The pacing, editing, and music were a little formulaic...but I suppose it being your first trailer, it does you good to mimic the pros.
Being a narrative, I'd love to see this cut together with some dialog...personally, I dislike when film makers edit their narrative trailers without a single line spoken...to me that screams red flag. It makes me wonder if the acting sucks, if the script sucks...and the truth is...implementing dialog into a trailer DOES give away certain qualities right away...that's why it's avoided by many beginning film makers. To me, however, if you are able to put together a trailer with dialog and it looks and sounds great and believable...that's when you are nailing a solid trailer.
Another thing, as Henry eluded to was that you have shots in the trailer that are there simply because they look cool. In my circle of friends this is called 'Masterbation material for DP's.' They don't move along the story, they don't express the narrative aspects of the piece...they are simply there because the shot is cool...
Good luck with future exercises.