Had a craving for one and remembered Limster praising the one at Flat Patties in the Garage in Harvard Sq so gave it a shot for lunch today while passing by.
Yummy. Very nice, moist, lightly coated and fried haddock that was fresh enough to be juicy with genuine flavor (a light clean faint taste of the sea - by that and the texture, this had clearly not been frozen into cardboard prior to cooking). Bun was nothing special - standard white sponge - but fish excellent and if I recall correctly, only $4. Not a supersized serving, but ample for lunch.
Came with cole slaw. Comes on sandwich or in a small cup on the side, as I had it, since I don't like most fast food slaws and didn't want to chance it ruining a good sandwich. Pleasantly surprised me by not being the usual tasteless, drowning in mayo glop - just enough dressing to hold it together, nice crunch, and the main taste was the peppery bite of the cabbage, as it should be.
I also tried a small order of fries, since others had praised them and while the taste was good, my sole quibble was that they were on the limp side.