The costume can certainly be picked-apart from photos, and rightfully so. But I'm most interested in how Vader looks in the movie. What I mean is, does he looks like Darth Vader or does he look like a guy in a costume. Given the differences between, for example, ANH and ESB, I'm more interested that in R1 he looks like Darth Vader and I'm less interested that he looks exactly like ANH.
Crazy theory, but I wonder if he wears both over the shoulder armor capes and under the shoulder armor capes. Wouldn't it be crazy if they had him in under wearing under the shoulder armor capes but the capes are trashed during a fight, and then they used the un-used footage of Vader that was shot in 1976 for ANH when he's in armor without capes just before the Star Destroyer goes after the Tantive 4.
If you don't remember the scene, I believe it's in the Star Wars storybook with a photo also. I'll try to dig up the photo tomorrow.