I just got this item and used it, but it doesn’t work. It doesn’t work for my guildies either.
The item actually does work (you are granted the additional appearances for slots you’ve already unlocked), but the effects are bugged and so you won’t see a difference in most cases. The fix is dropping next Tuesday with 10.0.5.
See this post:
I found the extra helm and shoulder options in my transmog, but the shoulders have no lightning at all and the helm lightning only shows up in the preview windows. I’m looking forward to next Tuesday.