I love this place, and if you avoid what I did during my last trip (thus the reason for knocking down one star), then you'll enjoy your visit here like how I usually do.
Came here for a late dinner, and the line was crazy long. I think my girlfriend and I ended up waiting in line well over an hour. Each of the previous times I've come to Oyster Bar, it's usually been in the morning or early lunchtime. The trick is to avoid the crowds, as I finally was introduced to the long wait that my cousin had long warned me about.
I ordered the Alaskan Chowder, New England style with an added side of pasta. I loved the idea of having a variety of seafood items in addition to the typical clams, but just found that the thick consistency with that large portion size to just be too much for me to handle. Maybe that's a quality that you like, but I'll order something else next time.
To review: plan coming here early, and don't order the chowder (unless you want to share).