My fiancee and I tried Bymark during Winterlicious this year. We made a reservation about a week in advance because we thought it would be busy. To our surprise it wasn't, which was nice. The restaurant was about half full that night.
Bymark might be little hard to find if you don't know where it is. We could have very easily taken a wrong turn in the PATH and they don't have very good signage on street level.
The service we received that night was amazing. In my fiancee's words: "We haven't been to a place where everyone knows what they are doing". We were offered a complementary coat check when we arrived, and promptly seated.
We ordered from the Winterlicious prix fixe menu, and we both had a wine that was suggested on the menu. Everything that we ate definitely left an impression on us. Even writing this review more than a month and a half after our visit, I can still remember the taste of the food. I had a the beef tartare, duck breast main, and gingerbread cake for dessert. My fiancee had the burrata appetizer, grilled branzino & mussels main, and apple crepes for dessert.
Our bill came to around $150 after tax and tip.