I don't think it should even be referred to as a remake. "Remake" implies it was rebuilt from the ground up, with significant alterations or enhancements. It is a HD port; still essentially the same game with minor graphical tweaks, so it can support higher resolutions. However, I have read it will be the "International version" which contains 9 new optional bosses, a few other changes, and an extended epilogue (which you can watch on youtube). Assuming that is accurate it's up to you to decide it it's worth paying for when you already own the game.
Personally, I liked the game overall (despite finding Tidus incredibly stupid and irritating protagonist and hating the whole blitzball thing), but don't have a strong urge to play it again. Of course, I hail from the "Final Fantasy is highly overrated camp". FFX is the only FF game I've tried that I've actually played to completion. But it's so linear I just don't know why I'd want to play through it again. Since it is supposed to have the international content, I may pick it up once I can get a dirt cheap used copy.