I was shocked when I saw that some visitors to Sam's Grill actually hated the place. I've been there several times and I've always been more than satisfied with both the food and the service. The decor is old time San Francisco -- not fancy, but homey. Beware of Friday nights, though -- the place can get very cramped.
The fried calamari alone is worth the visit. I've had the Ahi Tuna, the Ivory Salmon and the Lobster Newburg and they've all been first rate. The seafood salad and the clam chowder are great starters.
As far as the service, some of the waiters can be sort of brusque as some other reviewers have mentioned. However, to solve that problem, ask for Stefano who has a terrifically gregarious attitude towards his job.
Please ignore the negative reviews and give Sam's a chance -- especially for dinner. You won't be disappointed.
Pros: Food - Large menu, Old S.F. charm, Stefano
Cons: Not open on weekends, Can get cramped