Mel Gibson is a very talented filmmaker and ''Apocalypto'' is his best picture to date. It makes ''Braveheart'' look like a gentle comedy of manners, and ''The Passion of the Christ'' like a pleasant Disney cartoon. In other words, it's unbelievably violent. Set on the Yukatan peninsula during a particularly gruesome period of Mayan history, it shows a priest plunging a knife into a man's belly and, while the victim is still alive, tearing out his still-beating heart, and then cutting off his head, which bounces down the long steps of a towering pyramid toward a frenzied crowd below. Stylistically, it's a terrific action picture in the best tradition of the ''wham, bam, thank you, film editor'' school of Hollywood filmmaking, where the takes are short, the montage is frantic, and the chase is always on. In fact, the second half of the film consists entirely of one long chase sequence across jungles, corn fields, waterfalls, marshes and mass graves. The cinematography is breathtaking. The camera moves relentlessly through the densest of foliage and over the roughest of terrain, with marvellous crane movements and perfectly synchronized travelling shots. James Horner's musical score - full of threatening, choral-like synthesizer growling, woodwind interludes and alarming percussive strikes - further enhances the viewing experience.