The Ultimate line takes classic Marvel characters and ideas and infuses them with new concepts and in radically fresh ways, without the ties to continuity.
Reading Ultimates is like seeing the best widescreen, blockbuster movie come to life on a comic page. It's got all the action, suspense and intensity of a big-budget movie, with the intricacies you'll only find in a comic. If you like comics, you're pretty much guaranteed to like Ultimates.