It's never good when someone asks "what are they" like our Elvis 'ere eh? LOL
Seriously though, I would think twice (if it was me) having something so large is an area which can be viewed alot, think strappy tops in summer. You very well could regret it 10,15, 20 years down the line.
I personally think they're tacky (sorry), I would imagine that something so large and intricate would hurt, especially in that area, and it would be quite pricey. I got the teeniest one possible on my shoulder blade, and it cost me �25, so I dread to think how much they'd cost you.