I believe this version of Spider-Man, wearing a suit designed by Tony Stark (Iron Man) first appeared in the Civil War storyline. I didn't read Civil War, so I may be wrong.
I also think this figure is a re-release, but I could be wrong about that too. (Boy I'm real helpful today aren't I?)
This specific figure was just released as part of the Spider-Man action figure series, which appears to be a new series with a bunch of re-paints and re-releases of Spider-Man and Spider-villain figures. Be sure to keep an eye out for Scuba Spidey! *rolls eyes*
What makes this version unique (and this I'm sure of) is that he's made of a translucent red plastic!
The series also includes a painted red version, and I have heard reports that they are evenly distributed, but the translucent version is way cooler and the gimmick prompted me to buy him. He reminded me of the old Tron action figures.
"Doesn't anyone ever sweep around here?"
I don't know why Stark only gave Parker three extra legs instead of four.
Being a Marvel Legend type figure, Iron Spider-Man has like, fourteen billion points of articulation. This figure even has articulation for all eight fingers (sorry thumb fans!)
I really think they over do the articulation on Marvel figures; the yoga poses only make sense for Spider-Man.
I imagine the translucent nature of this figure is representative of some stealth mode that the suit has. It was made by Tony Stark, I'm sure it does all kinds of wonderful things.
All in all a fun figure and a cool alternate Spider-Man. And at least this costume is relevant to actual comic book appearance (I'm looking at you, Anti-Freeze Batman!)