Agreed on the Rebellion bit John... That actually has a LOT of importance. First, it establishes some "scale" to Star Wars... The petition of 2000 kind of shows the viewer that the Alliance is a "pitiful little band" compared to the Empire... On the grand scale of things though, the Alliance is F'n huge itself. It would rival the CIS as far as its ultimate threat to the Empire and it gives some real "meaning" behind the Empire wanting a Death Star. To me it even reinforces a 2nd DS as being something worth investing in for the Empire as the Alliance is an already large, and supposedly growing body.
The acting was a little eh... I didn't mind Smits and felt his acting was intentionally "coy" more than "bad". The worst dialogue delivered in the sequence was Lucas's older daughter... Good lord must his kids get their usual cameos like this? Her stupid look at the screen in AOTC, and now her asinine acting job. One line and it sounded forced! That's almost worth giving her her own award for.
Yoda's scene is kinda cool. That's the most deluxe escape pod in history it seems.
Shaak's scene could've been edited down a bit and reinserted. It really, to me, is the scene out of them all that is necessary to improve ROTS whereas the others could be missing and not have any major impact... I like the Rebellion scenes but ultimately they don't really change much that's important overall, however Grievous' character is established as a little more of a badass in his executing Shaak sequence, and that's something his character desperately needed.