I have one Yema: the grey / blue GMT. It has been quite a headache, but after 9 months and 3 round-trips between the US and France (not including the original shipment), it's finally functioning correctly and I can wear it. Honestly, it's been such a pain in the neck, that it makes it more difficult to enjoy the watch.
I first sent it back, because it was gaining over 40 seconds per day when I received it. When I got it back the first time, the GMT hand would jam. When I got it back the second time, the GMT hand was still not functioning correctly - it was no longer jamming, but would "click" and not advance. On the third return, they decided to replace the movement, and it seems to be functioning well now.
They sent me this box along with the watch in the last shipment. It's quite nice, and I guess it's their way of saying, "Please continue to be our customer."
They also gave me some bonus points in their membership program for my hassle. However the program changed recently, so I'm not sure how much those will actually benefit me. Previously, I could have cashed the points in for a $100 coupon, now I have a status that gives me a 12% discount on purchases. They don't currently have many watches in the $1,000 range that I'm too excited about.
Their customer service has been pretty good, so I'm not swearing them off forever, but they're not very high on my WTB list at this point. And I definitely question the competence of their watchmakers.
Maybe I'll try to pick up a couple vintage Yemas to fill out the box.
Here are pictures of the watch in question.