It 'did' seem a little rushed for episode 3
It's like....Darth Vader's costume looked so bad-ass like a space samurai war-lord. The helmet looked too 'formal' for it to be placed on a whim. *(Obviously they did it for time constraints without making Episode 3 part 2)
A transition costume would've made more sense....AND would've totally 'nerd-raged' out the fan-base with senseless arguments like 'who's better'.