I've been a fan of Fresh Pond Seafood for a long time, and loved their fish shack when they were at Fresh Pond circle in Cambridge. I was a bit wary when they moved from a busy street to a side corner in Arlington, since everybody knows that turnover is important when it comes to getting fresh fish. The selection in the new place seems to be a bit smaller than in the former location, and the prices are a bit higher, but the fish I've bought over the past year or so has been great.
They've also added a small seating section and now offer some broiled and fried fish as well as chowders. It's wonderful to be able to get high quality fried clams right down the street!