He's mostly pretty awesome, except for Ashes of Time, which is fairly incoherent.
Hierachy, well for me the three 'must see' Wong films so far are: Chungking Express, In The Mood For Love, Happy Together
Then the next 2 are exceptional, but not his best: 2046, Fallen Angels
Then there are a couple of his earlier films which are good, but lack the polish and intensity of his more recent work- As Tears Go By and Days of Being Wild.