The story behind the creation of The Gambler is well-known--due to heavy debt, Dostoevsky had less than four weeks to write a novel to avoid losing the rights to all his works, both past and future. To make his task a bit easier, he hired the star pupil of a stenography school (whom he later married) to take dictation, and for the material of the novel he borrowed heavily from his own life--he had experience as a compulsive gambler, and he used his mistress Apollinariya Suslova as a model for the character Polina.
The result was an inspired, though by necessity short, work of art. The passages set in the casino do an excellent job of capturing the tortured fascination that gamblers have with the roulette wheel even for readers, such as myself, who have avoided casinos all their lives. However, The Gambler is not just about gambling--it features an intriguing array of characters which are developed quite well in the mere 117 pages of the novel. "Granny," for instance, is probably just about the most amusing character I've seen in Dostoevsky, and the entangled aims of all the characters make for a very lively narrative. It seems as though, if he had the opportunity, Dostoevsky could have written a whole novel about any one of them.
Obviously, The Gambler lacks the depth and brilliance of Dostoevsky's more famous long works, but if you're after a quick, entertaining read, it's really an excellent choice.