It’s tempting to say that Quentin Tarantino has too many ideas, but that’s not quite right. Certainly every one of his films has been overstuffed, at least after his comparatively lean debut, 1992’s Reservoir Dogs. Even the one film of his that I think approaches genuine cinematic genius, Pulp Fiction, has elements requiring a certain amount of forgiving patience (if I’ve seen Pulp Fiction a hundred times, then I’ve skipped Bruce Willis philosophizing in the taxi cab with driver Angela Jones about ninety-eight of them). The problem, then, isn’t that he has too many ideas, but that he’s apparently incapable of discerning between the good ones and the bad ones.

For most of the running time of Django Unchained, Tarantino is brimming with good ideas, and he’s executing them well. Jamie Foxx plays the title character, a slave in the American South, in the years immediately preceding the Civil War. He’s liberated by a bounty hunter named King Schultz, played by Christoph Waltz, who needs some information, the visual identification of a trio of brothers with an especially lucrative prices on their heads. When Django proves to have something of an inherent skill at gunning down quarry, King takes him on as a partner, with the eventual goal of tracking down and freeing Django’s wife, nicely played by Kerry Washington in an underconsidered role. The film rapidly turns into another one of those firecracker amalgamations of all the messy movie memories that keep Tarantino’s brain permanently asimmer. It’s a buddy picture, a spaghetti western, a revenge saga, a blaxsploitation barn burner and on and on.

It’s also a little more disciplined than Tarantino’s recent efforts, downplaying the self-conscious signifiers and mockable meanderings that made Inglourious Basterds, for example, a masterwork marred by a crust of blasted snotball indulgences. The floridness of his writing is toned down, or is at least caressed into an amusing, pleasant, surprisingly natural flow by Waltz, who has taken only two films to establish himself as the best interpreter of Tarantino’s words that the filmmaker has ever had. Waltz plays King as a kind soul who has paradoxically found himself in a brutal business, couching his actions in the sanctified logic of the law. Every scene has a hint of discovery, of a man trying to work out a moral code in a landscape pockmarked by ugly inhumanity. Foxx is also quite good early on, especially in the scenes in which Django is trying to register what’s happening as the world shifts beneath his newly unshackled feet. The performance grows progressively less interesting as the film goes on, presumably because Tarantino’s direction amounted to little more than, “Now you’re the baddest motherfucker around,” and Foxx ran with it.

There are other small hitches–the bloat of a nearly three-hour running time sometimes weighs on the film, and Samuel L. Jackson plays his admittedly fascinating character with a wholly predictable mannered menace–but the film doesn’t slip its groove completely until the last reel or so, when Tarantino pointlessly prolongs the mayhem. A colossal shoot-out at the plantation run by a sadistic dandy played by Leonardo DiCaprio (having fun, but it’s ultimately a negligible performance) could have been conclusion enough, with its heavily stylized violence and turmoil of thematic comeuppance. Tarantino drags it out as long as he can, though, with a circuitous route to the actual ending committing the cardinal sin of being dull. (It doesn’t help that this passage also creates room for an abominably bad cameo by the director, who really needs to hire someone whose sole job is to flatly refuse him anytime he expresses an inclination to give acting another whirl.) I expect to go through a lot of sensations while watching a Tarantino movie, but boredom isn’t one of them. For most of its healthy span, Django Unchained is far from that. But it’s hard to let go of the final impression it leaves as it drags painfully to the end.