In the long line of Squaresoft goodness, Final Fantasy X is the tenth installment of their conjoined disjoint series.
Like all of the other Final Fantasy games there are similar themes with the other games. A hero against an insane villian bent on destroying or ruling the world(which ever comes first). Just like all the other FF games the differences are what define this game.
One feature I really liked was that the 7 playable characters are distinct(at least at the beginning) and can be swapped in and out during your turn in combat. Each of these characters also have distinct roles. Tidus is fast and is often the only one able to hit highly agile monsters. Wakka can hit monsters in the air or far away. Yuna takes on the dual role of white mage/healer caster and summoner. Lulu is the black mage exploiting elemental weaknesses in monsters. Rikku is the thief able to use thieving abilities like Steal. Auron is the warrior monk with high damage and high defense but slow attack. Kimahri is the multipurpose blue mage and lance wielding knight.
Another feature is the advancement system called Sphere Grid. As you move through the game and defeat monsters you pick up spheres where you can place in nodes on the path in the Sphere Grid. Technically all skills are available to all characters but the distance for Auron, for instance, to travel to get to the Yuna's healing nodes is very far and expensive to achieve and therefore not practical.
It is also a very pretty game featuring lots of the latest technology available on the PS2. Characters in combat insert verbal quips. The movies are all CG rendered. All sorts of fun stuff.
One extra thing to mention: I felt the battles were more strategic due to the change from ATB System to a far more strict Turn Based system. You can only have 3 characters present in the fight to face the monster but as mentioned before you can swap any of the other 4 in on any character's turn. Random encounters usually generate monsters that are not weak to just one type of attack. The strength in this setup is that one must consider the foes your team is facing and plan ahead moves which was only vaugely available under the ATB. Some creatures have strong defenses against all attacks except for one available to only one of the characters. Swapping the strong ones in and the weak ones out at the right moments is often key to surviving harder encounters late in the game. I definitely liked this feature more than the repetitive and mindless button mashing you ran into in previous FF games. Of course I'm not to hip on the random encounter thing anyway but at least this breaks some of the monotony.