I tried Flixster but I didn't like the way it is set up. You basically see two movie posters and pick which film you like better. It then reloads two new films and you repeat the process. It becomes monotonous after a while. At least with Criticker you can filter by actor, director or genre and rate multiple films.
Stange, that is not how I remember the Facebook app; I haven't actually used the site itself, but I also have the iPhone/iPad app. Anyway, there I would get lists of films and if I had seen them I would rate them with up to five stars (half stars available). In the iOS versions the rating can be slightly more cumbersome, but at least you can search by title.
If the site works/worked as you say than that is indeed rather stupid. Just comparing two films doesn't end up creating a profile of your taste...
While it would mean I'd have to start over, I'll have a closer look at Criticker.
EDIT:
Signed up; username ya_shin. Haven't rated anything yet, as I am not used to rate on a scale from 0-100. Then again, I could just use round numbers...