I find the Order66 scenes really well done. The music, of course (thanks John Williams!), is really touching, and the way that the Jedi are wiped out (Clones under their command, killing them from behind) is really sad. Watching extremely powerfull characters being killed by cowards has touched me.
I was waiting to see that from the very begining of the PT and, even if it doesn't take place like the way I was imagining it, I think it's one of the best parts of ROTS.

But, well, I must say that I don't really like Aayla Secura's death just cause of the Amy Allen acting: she has no expression, and fall down really too fastly IMO...
Kit Fisto and the two other Jedi are also killed really too rapidly and too easily by Palpatine. Too bad...