This is just getting stupid.
Final Fantasy XII does not play like .hack. The .hack series features real-time, hack & slash, button-mashy combat, and is a dungeon crawler. While it attempts to mimic an MMO, it does so in atmosphere only, and not in gameplay, so there won't be any comparisons there either. What similarities you're left with are pretty common elements, like the large field maps filled with respawning enemies, and a party of three characters -- that's about the extent of it.
Final Fantasy XII plays more like Final Fantasy XI than anything. While combat is similar to that in FFXI, it builds upon it by allowing you to see your ATB bar, cancel commands mid-charge, queue-up secondary commands, switch between your party members with the D-Pad at any moment, etc... In essence, it's the typical ATB battle system in reverse, with some real-time elements (such as movement) and a Chrono Trigger-style command menu set-up added on-top.
There are also a lot of elements running outside of combat that mimic FFXI/MMOs, such as aggro schemes (on sight, magic usage, etc), linking schemes, EvE schemes (ie: Mandragoras will attack Sleipnirs), etc... Absolutely none of these have been present in a single-player RPG before, and that's what sets it apart. There are also other elements that aren't really active, or available for tweaking, in the demo, like the Zodiac Sign system (from FFT), the Gambit system, and so on, so it'll remain to be seen how well they'll turn out or be utilized.
Given the over-leveled nature of your characters in the demo, though, it doesn't force you to use any of the systems in place... which is a shame, as you get a bunch of retards not even noticing that these things are present. Even people that have played through the demo half a dozen times have looked at me funny when I mention that Bombs will aggro magic usage -- "No they don't, they aggro on sight." they say, which is exactly what prompted me to post my mini-FAQ in the demo impressions thread, as I noticed there were 3-4 pages of such comments. And nevermind Tycho's non-grasping of the demo mechanics over at Penny-Arcade, where he spends his entire rant bitching about the game taking control out of his hands, when in reality, it's giving you more than the typical ATB set-up ever allowed for.
When it comes right down to it, I'm beginning to think that nobody knows how this game plays...