It kinda needed Tarkin. Otherwise you'd have to go out of your way to write in/explain his absence. "Yeah, Tarkin would be here to witness the testing of the Empire's new shiny toy but he took off to Hoth for an ice fishing trip"..
I thought Leia's appearance was alright, reanimation-wise.
So.....
..
.
How about them last 5 minutes?..