I had no idea Tarkin was going to be in it at all, but now that I know he's in it, I wish he had more screen time and maybe a line or two.
I thought everything was fine with the Darth Vader scene except two things. 1. Why would Palpatine tell Vader he killed Padme? I just don't understand that. 2. The "Noooooo!" line was really dumb, though the more times I watch it, it doesn't get better, but it gets more bearable.
The lack of Shaak Ti was dissapointing, but nothing that would make me dislike the movie completely.
Although I've come to accept the "force memories" theory, I still think it would have been better if Padme had lived on so Leia could remember her.
There were some other things that could of been improved, but besides the things I listed, nothing else really struck me as being stupid or dumb.