Although it's a 2 hour film and I'd seen (but forgotten much of) it before, time flew past... not a single dull moment.
Some of the over-the-top, 1940's script was funny, if obviously unbelievable, such as when Spade passionately kisses Wonderly and all of the quasi-romance that ensues; at film's end Spade seems to actually contemplate letting Wonderly off the hook for killing his partner! LOL.
I especially enjoyed the Gutman character, excellently portrayed by Sydney Greenstreet.
Kasper Gutman : You're a close-mouthed man?
Sam Spade : Nah, I like to talk.
Kasper Gutman : Better and better. I distrust a close-mouthed man. He generally picks the wrong time to talk and says the wrong things. Talking's something you can't do judiciously, unless you keep in practice.
[sits back]
Kasper Gutman : Now, sir. We'll talk, if you like. I'll tell you right out, I am a man who likes talking to a man who likes to talk.
Sam Spade : Swell. Will we talk about the black bird?