I finally saw Manchester by the Sea. Casey Affleck's performance is exceptional. I was also very impressed with Lucas Hedges' performance. The film itself, while very good in exploring dealing with grief, has some writing and stylistic flaws (although I thought the dialog between the characters was well done). This is one of those films you can't get into without giving it all away. So rather than do that, I will recommend you go out to see it or rent it.
Rotten Tomatoes: Manchester by the Sea