I have mixed opinions on this - it feels like a cosmetic solution to a somewhat non-problem.

Would I carry it?

As of yet - no, I would rather use iphone apps etc.

The other problem that it misses is the show that people like to make of using a certain card.

I have an amex platinum for business purposes, but I still get a bit of thrill every time I use it and I get a look, how does Coin approach that problem?