Most people who dislike Brussels Sprouts have probably only tasted ones that were severely overcooked, or were too old when prepared. Don't keep them (the sprouts) more than a week, and make sure you blanch/boil them in plenty of water, just until a fork pierces them (the people) smoothly. These are good tips for all cruciferous vegetables: Broccoli, cabbage, and brussels sprouts will all develop a nasty sulfurous aroma if abused.
Brussels Sprouts can also be cut in half, brushed with oil and sprinkled with salt, and grilled or roasted. The outer "leaves" may need to be peeled off.

Brussels Sprouts at their best are not mushy, but shapely and tender. They have a mild taste, not sharp or sour. They taste like slightly sweet cabbage, but if you haven't had good brussels sprouts you probably also haven't had good cabbage.

Once you've enjoyed brussels sprouts, you can observe the revulsion on others' faces and say incredulously, "how can you not like brussels sprouts? It's like putting an entire cabbage in your mouth at once!"
This, to me, is reason enough to make the effort.