I've been loving the Fish Store for years now, but also possibly subconsciously forgetting to Yelp about it (online anyway, I've taken at least a half a dozen friends here in person) because they have very limited seating. In warmer weather, sitting outside on the benches or taking out to go al fresco are lovely options.
In the winter though, when the (arguably) two two-tops that are available inside the wedge of a store are taken, your only option is to stand in the doorway and withhold your salivations while waiting for take away. Luckily, since they only take cash, you'll most likely have to take a jaunt over to a nearby bank which will kill some time.
My all-time favourite default order is the big juicy scallop sandwich, but every time I stare up at the laminated photos, I swear to myself that I'll try a shrimp or fish burrito next time. The potatoey clam chowder is nothing to write home about, but does the job to warm you up.
It's really nice to have a selection of fresh fish to look at when making your decision. Take advantage of this (or just order the scallop sandwich every time and never have anything to regret).