The title pretty much says it all. Post your two cents if you like, but remember that if you want to defend the game, you're in for a severe uphill battle.
Story - It's obvious that the story is influenced heavily by those of western RPGs. And therein lies the problem. It's a Japanese game. A Japanese game should have a Japanese flavor. When it doesn't, things go wrong.
In this case, the failing is simply that FFXII is NOT a role-playing game. It is an adventure game, just like the majority of its predecessors. RPG scenarios and adventure game scenarios have to be designed differently. In the case of RPGs, development of the main character is left virtually untouched so that players can fill it out through their own actions. To make up for that, the focus is placed on developing the setting, scenario, and secondary characters. Of course, in most successful RPGs, those elements are also flexible and change depending on the traits you display through the main character's actions.
Adventure games focus more on the main character and are absolutely rigid in terms of plot progression. That is, of course, the way the Final Fantasy series has always been. The primary characters in adventure games are usually very well-developed and a great deal of time can potentially be spent exploring their personalities.
In FFXII, the focus is likewise placed on developing the setting and scenario. The problem is that the characters are pre-defined. They lack the depth and appeal of adventure game characters and are more in line with side characters in an RPG. If the Japs want to make a role-playing game, they should try to go all-out and make a real one. Don't rip the worst possible element from them and trust that a flashy execution will make up for it and convince people that different is good just because it's different.
Gameplay - Using a system basically taken right out of a MMORPG was a great idea. Breaking it with quickenings was an abominably bad idea.
I heard before the game was released that it was actually pretty hard. Imagine my surprise and outrage when I discovered that the people who made that claim were full of crap. Once you have quickenings for a few characters, the game becomes ridiculously easy. And don't even start with that nonsense about not using them to make the game harder. The objective of any game is to win, and it only makes sense to use any means at your disposal to achieve that goal. If you deliberately hold back to make something harder, it means you've acknowledged its failing on some level, even if you're not totally aware of it.
Also, gambits are nice, but there just aren't enough of them. What's more, the developers knew that and specifically designed it that way. It's obvious from the fact they limited the number of them that you can use, especially at the start. Their objective was to hold players back from doing as well as they possibly could to make the game more difficult and try to give the illusion of depth by making you find or buy new gambits. If the system was fully accessible right at the start and gave players dev-level control over the AI of the characters, it would have been ideal for a game that was more well-designed all around.
Secrets - I know I've made this rant before, but it sucks when developers hide things in a game that no one in their right mind can possibly find without some kind of guide. The series started doing this with FFVII (which was perhaps the first game to be aggressively marketed along with a strategy guide at the time of its release) and has gotten worse with almost every subsequent entry. If you hide things in such a manner that people cannot find it without a guide, you're basically locking away part of the program that they've paid for and telling them they have to shell out even more if they want it. It's only a step short of extortion.
I have other complaints, but this is pretty long already.