This is the first game I bought when I got my PS2 several years ago, and even though I own more than a dozen other RPG titles, this one still tops my list of favorites. For immersive gameplay, excellent character development, graphics, sound etc., this game is amazing.
The cut scenes are gorgeous... I can't wait for the day when technology allows all gameplay to look like FFX cutscenes! The graphics throughout the rest of the game are also excellent. Slight "jaggies" here and there, but that can easily be forgiven, and is definitely not and issue, given gameplay.
The FFX story really draws you in. Given the bittersweet ending, it's no wonder Square decided to follow up with FFX-2.
The levelling system is good, and menus are easy to master early on. The mark of a good, intuitive menu system is that it doesn't interfere with gameplay flow, and these don't. Well.... The Spheregrid can annoy at first, but ultimately it is a clever system, because it requires strategy to determine which direction in which to develop your characters.
This game is so good, I've played through twice, and intend to do so again before FFXII comes out. Heck, even Blitzball, one of the weakest aspects of the game, can be fun and addictive, if you give it a chance.