Adaptation Displacement: The film is much better known that the original play. It's not particularly surprising given the differences in the medium, the all-star cast and the general improvements Mamet made in the film.
Crosses the Line Twice: The constant berating is nothing if not unique, which makes some of the insults stinging and hilarious, such as Roma's disdain for an Indian client, stating that he was so stubborn, not even the Indian gods could get him to sign a deal.
Ho Yay: Roma's seduction of a customer isn't subtle.
How the Mighty Have Fallen: Levene is said to actually be a pretty good salesman who's currently stuck on a bad streak. You can see how he actually is a jerkass under that sorry exterior as soon as he thinks he's back on a roll.
Shelly "The Machine" Levene. In spite of the way we can see how sleazy he is by his sales tactics, he's such a sad-sack with a sob-story that we can't help but feel sorry for him.
Roma and Moss probably also count since the former gets screwed out of a $6,000 deal thanks to Williamson and the latter gets implicated in the robbery by Levene.
Jerkass Has a Point: Levene's comment to Blake on the leads being too weak to fulfill. When he closes a big deal that boosts his confidence once again, Williamson shoots him down at the end by telling Levene that the lead was a dud and Williamson had known for months. Which means for all their complaining, the main characters were right about being held back by bad leads.
On the other hand, Shelley either forgot about or didn't read an important memo "never sell to these people" and was too self-deluded to notice that there was no way his clients had 200 grand lying around to invest in real estate.
Magnificent Bastard: Ricky Roma, who artfully manipulates a potential customer while riding his hot streak.
Misaimed Fandom: Not only is the film loved by the very Salesmen it sets out to destroy, but Blake's scene (which is intended as characterizing pretty much everything wrong with corporate America) is used as a motivational tool in workplaces. Of particular note is a Cracked.com article (see Memetic Mutation above) where the author pretty much uses the scene to describe how one might become a "better person", when David Mamet has openly said he intended that scene to show what was wrong with rampant capitalism and cutthroat sales tactics. To be fair, David Wong also emphasizes a lot in his article that making money alone doesn't make you a better person and explicitly uses the scene as a metaphor (his point is essentially an Anvilicious "It's not who are, it's what you do" message).
One-Scene Wonder: Blake's scene in which he completely berates the office staff for their failure to perform. Especially notable as it's original to the film adaptation.