Wow, all I can say. There is no backbone for your argument other than you think yourself to be a star wars specialist.
The music was basically the same as it is in every other star wars film, same style at least, in fact I really liked the main theme, it built off of the trademarked star wars theme.
It would have been really silly if Vader just all of a sudden popped up at the end, in his ship, and took co ntrol of the while scene. From my perspective, having Vader in the other parts of the scene showed his prominence.
How can you say the space battles were horrible? Did you fall asleep during that part too?
Using the hammerhead corvette was creative and fresh, as the brought in aspects from the universe we haven't seen. Also, these ships are known to have very powerful engines, think of them as a tugboat, and they were design to work on a skeleton crew, hence the suicide run. It also depicts how desperate the rebellion was to get those plans.
Finally, you probably thought it was boring because you have read into the cannon universe, there we sooo many ties.