Anthony Burgess's novel "A Clockwork Orange" is one of those books whose appeal is mostly derived from its ingenious use of language. Accordingly, any visual interpretation stands to lose much of the impact of the original work. However, with a visionary like Stanley Kubrick at the helm, the results can be equally great in a different way.
Kubrick wrote the screenplay himself and he managed to retain enough of the book's unique language to give the film a sense of the novel's style. Burgess wasn't happy that Kubrick dropped the events of the final chapter of his novel but I feel that movie's ending is more effective. Overall, a challenging adaptation for which Kubrick was rightly rewarded with an Oscar nomination.
As for the direction (also Oscar-nominated), Kubrick delivered a typically outstanding effort. His direction is arguably as dexterous as Burgess's prose. The cinematography is also stunning while the score, which is rife with classical music, is memorable as well.
As far as acting goes, this is Malcolm McDowell's picture. That's not to say that the supporting actors are forgettable (they aren't); he just delivers a towering performance that few could hope to match. The fact that he was denied an Oscar nomination for his work is nothing short of mind-boggling.
Ultimately, "A Clockwork Orange" succeeds both as entertainment and as a piece of art. The novel is a tough yardstick to measure up to but Kubrick accomplished the task mainly by remaining true to the source but also by adding a few touches of his own. I highly recommend it as one of the best films of the seventies.