I have one for my RC300h F-Sport, it came with the Takumi pack. I've never used it, not sure how useful it is TBH. One cannot use it to remote open the boot, or global opening of windows and moon roof.
Sure it doesn't leave a bulge in one's trouser or jacket pocket but I wouldn't like to put it in my wallet, would it scramble one's credit cards? It also seems quite fragile, sit down with it in one's back pocket and snap!