This is a particularly great stop if you have canine friends in tow (a couple of ropes to tie them up, inside a nicely marked area keeping them away from the parking but close to the outside tables). Small pans are available for giving them water as well.
The patio is a glorious place to sit in nice weather, and the food is very good. Seaside, sadly enough, is afflicted with the thick slop clam chowder, but the U Street Pub does it right, with nice bacon flavoring, cream, and glorious flavor. The best Boston clam chowder I've had in Seaside so far.
Good service, good portions, reasonable prices. I've tried quite a few places in Seaside, and this is currently in my top two. Might not like this place if you don't have a sense of humor, though (one of their signs proclaims their fondness for gluten and love of meat).