Just saw the entire Infernal Affairs Trilogy. Infernal Affairs 1 and 3 were absolutely superb. Asian and Hong Kong Cinema at it's best.
I don't think The Departed will be nearly as good now
My ratings:
Infernal Affairs 1 - 9.5/10
Infernal Affairs 2 - 8/10
Infernal Affairs 3 - 9/10
Loved Infernal Affairs, loved it!