XII isn't perfect, but the overall game lives up to the franchise
FFXII is a highly well-crafted RPG that any fan of the genre should enjoy. I'll evaluate the game category by category.
The combat system (called gambits) is unique from other games in the series in that you program a lot of the characters' actions before battle. This can be confusing at first, but once you learn how to use it, it cuts out a lot of the micro-managing of past games. You can also stop the game to enter commands as well. However, the downside to the system is that magic is too weak relative to melee attacks, so it does not provide much incentive to use the various cool spells you have. The player ends up relying too much on gambits. Overally, I have mixed feeling about the combat system--I think it's a solid start, but needs to be more balanced toward magics and techniks.
Also, the summons in this game are virtually useless, and given that they look so stunning, it's really a shame.
Which brings us to graphics. FFXII is without question one of the most gorgeous games on the PS2. The animations are extremely well done and the world is just rich, vibrant, and colorful. Overdrive "quickening" attacks are stunning to behold. Also, the architectural style is simply inspired. Sometimes when arriving at a new dungeon, I just had to stop and gape with my mouth open at the design. There are influences from the ancient Egyptians, the Mayans, modern architecture, and much more. The entire world is just so detailed, you can tell the team spent a tremendous amount of effort. *applause*
The music in the game is good, albeit not my personal favorite--but it fits the game's setting well. Also, while the story was well-told, it wasn't extremely engaging, and the characters' personalities weren't developed to their full potential. Nonetheless, there are some characters you'll come to like (Balthier should've been the star!) :P
And as for value--you get a hell of a lot of game for your buck. It took me 100 hours to complete this game, and I didn't even do all the side stuff.
To sum up, if you own a PS2 and you enjoy RPG's, you should definitely give FFXII a try. The gameplay is flawed, but the overall experience is one you shouldn't miss.