The 2 pros about IMDB are:
- the number of people
- for a particular movie, the thread is always there ...
(yet this is also a cons)

The 2 cons are:
- in the OVERALL message boards, a message always got "submerged" and "disappeared" very fast
- in the INDIVIDUAL MOVIE message board, it is focused but after a while, one will NOT access the particular movie to read or post. In a way, you might not be able to contribute if someone watches the movie much later than you. Conversely, you might not be able to get the replies if you are one of the latest to watch.