This place is a mussels factory that uses a very straightforward aand effective approach. There are five price tiers, with three or four varieties of mussels in each. I had the $22.50 "Italiano," (calamari, toasted garlic, red wine, tomato sauce). The portion was generous and the preparation excellent. There are other offerings, including a few that are non-seafood, but mussels are clearly the main event. The fries are great, by the way.
The somewhat sterile atmosphere cost Flex one star in my book. Note that there are several locations: This review applies to the W13th Street location.