I've been meaning to try this place for a couple of months, due to the long lines I see at the ordering counter when I drive by. Jeffrey's is a Happy Days Diner-style burger place. Pretty typical diner menu with burgers, dogs, fish/chips, fries, onion rings, shakes etc. Loudish 50's and 60's background music although it is always great to hear the original Charles & Inez Fox version of Mockingbird.
I ordered a burger medium rare, fries, rings, large drink. About $11. Logistics are: order at the counter; they will deliver to your numbered table. Something logistically inefficient here as once your food is delivered, you then must then get up and walk across the room to the condiment bar. Condiments included freshly-sliced tomatoes & onions, sauerkraut, various types of pickles, and salsa.
Burger arrived med to med-well (nobody seems to be able to cook a MR burger on the peninsula), fries fairly thick-cut, rings good, but slightly overcooked. I thought the burger was good -- I'd guess 1/4 to 1/3 lb, and it tasted like chuck which I much prefer to sirloin for burgers. Service was efficient -- they seem to have their act together far moreso than the Counter which still can't seem to figure out which tables to deliver which meals to.
All in all, a decent burger place ... I'd give it a B.