From a distance they have a realistic look, but until you get close, you realise that they are tattoos. In terms of staying power, I would say the Chanel tats are pretty weak. As you can see in the picture, the top chain (with the Chanel charm link) rubbed off within four hours. The others however, had a little better staying power - I've had them on for a day and only the bottom of my wrists has rubbed off.
I like that people are bringing temporary tattoos back. They're an interesting spin (especially for jewellery) and add an edgy twist to your outfit. Also, the fact that the temporary tattoos are so ephemeral and customisable makes it even more fun to play with - everytime you put on your jewellery, you'll be able to change it and make it your own (the ring on my fourth finger was a small piece of "chain" I cut out from a longer chain) It's like being four-years old again, playing with temporary tattoos - except edgier, you almost get to play the part of a jewellery designer!
However, since the Chanel tattoos are a limited edition, I don't know if you can still buy them. Another option is Urban Decay's line of temporary jewellery tattoos that is selling for about HK$155 (US$25 + shipping cost) which is a cheaper and more readily available option.
For now, I am definitely loving the look, I can't wait to play around with my tattoos more!