I was rather impressed with the majority of the clone trooper shots (at the time I thought they were men in suits in close ups).
Perhaps it was the less convincing backgrounds that made them seem more real than the rest of the elements.
I really liked it when the dust kicked up from the fallen Trade Federation sphere because it made even the battle droids look more real by removing the garish looking landscape.
The Wookiee battle in ROTS look more realistic largely because the backgrounds were based on photographic plates which gave the light renders a more naturalistic palette.
I know these are alien worlds but just dropping a terracotta tint over everything is a bit lazy.