I don't care what anyone says, Jackie Brown is Tarantino's best picture. It is also, coincidentally, one of the last movies to feature a not-phoning-it-in De Niro performance. Playing against type as a dim-witted, low-key, low-rent criminal, De Niro stuns with his subtlety. And he sets the tone immediately with his introductory scene.
Now this scene is rightly known for Samuel L. Jackson's powerhouse soliloquy on firearms. And though Jackson's performance here—as in the rest of the movie—is riveting, De Niro's understated performance tends to suck me in. I love how comfortable he is with fading into the scenery, with not controlling the scene. Aided by only a few lines of dialogue, De Niro's performance consists mostly of facial expressions and body language. Slumped back in the couch, he resembles a stoned friend you brought over to play Xbox (that's what the kids are doing nowadays, right?), rather than an ex-con recruited for criminal shenanigans.
Note also, De Niro's expresion when Tarantino works out his foot fetish proclivities via Bridget Fonda's playful toe-tap of De Niro's scotch glass. De Niro is unsure how to react to Bridget's playfulness. His subtle expression could signify intrigue, caution or disgust. Or maybe all three. With his eyes, De Niro asks, "Is she flirting? Do I want a goddamn toe near my drink? Fuck it; I'll just quickly take my drink away."
Sure some could claim De Niro was merely phoning it in here. How hard's it gotta be to sit on a couch and pretend to be interested in some speech about guns, while drinking from a toe-touched glass? Now I ain't no actor, but I'd imagine it takes a lot of effort to believably feign such little effort.
[Unfortunately, this youtube clip doesn't contain the entire scene, but it contains enough for you to get the gist.]