Out of all the Final Fantasy games, Final Fantasy IV is probably the one that had the roughest ride over to the US (not counting, of course, the ones that were never made it over in the first place). The original US version was butchered, with the story muddled in bad translation, gameplay elements were taken out because they were either thought to be "too complicated" or "too religious," and the difficulty toned way down.
The game has been re-released and remade a couple times already, so how does the latest version for the DS stack up? Pretty damn well, as it turns out.