Do you know what Americans traveling abroad say about English food? It's bland, greasy, and overcooked. Unfortunately the Fat Squirrel reproduces those undesirable aspects of English cuisine on a regular basis.
It's too bad, because on first impression, the Fat Squirrel looks like a fun place. There are tons of different beers on tap and the bar patrons look as if they are enjoying themselves. However...if you wish to sit at a table and eat lunch or dinner with your family, be prepared for a different experience. I've been to this restaurant a few times. The first time (when it opened), the food was delicious and the service was great. The second time, I brought my extended family and was appalled. All of the food was bland and overcooked, and the roast beef tasted rancid. The waitress visited our table only once and was rude. We gave the Fat Squirrel a third try, hoping our last experience was just a fluke. Not so--at least three of the items we tried to order off the menu were "no longer being served". When we finally did find something that was being served, it took over an hour to come out of the kitchen and was just as bad as the last time. We ordered all ordered meat dishes and did not have the fish and chips.
The pub is probably worth visiting if you like beer and feel like socializing. A lot of people seem to like the fish and chips, so perhaps that is something FS does well? I personally prefer the Turtle Mountain Brewing Company (I think I heard that it was owned by the same people?). It has the same fun atmosphere, but the food is much better.