Disappoint? Not really.
I will say that this is hands down the most DIFFICULT final fantasy of all time. It doesn't help that you game over when your main guy dies no matter how the rest of your party is doing. Enemies PUNISH you on a regular basis. Eilodon fights are rather difficult to figure out on the first go and even then you have NO time to experiment because of the doom counter on top of your MAIN CHARACTERS head. The scoring system is unnessesary and insulting. Seriously, what are these points for? I know that you get your TP back faster if you score high, but I generally don't care enough to die in order to pull it off.
Combat comes down to some simple mechanics. If the enemy is not staggered you will do crap for damage, so punish a single enemy until it is staggered. Later you can launch it in the air and juggle it with spells and attacks until it is nothing. You can't actually chose your leader until chapter 10, so whoever the game wants you to play, you are stuck with him (like hope or vanille). Paradymes are nice, but whenever the game switches some vital characters into your party you gotta remake the ones that are actually good.
The story is pretty good. The whole '13 days' thing confuses the crap out of you for a good chunk of the game. Cinematics are all top notch. Eventually everyone gets connected in some way. While Hope seems like a useless twit for much of the game, most of the others grow on you. You actually get a much better idea of who these six characters are in the first 20 or so hours than you do in the entirity of ffxii for vaan and penelope. For much of cocoon your team is not united in cause or even traveling together. You can't really hang out and shop in towns because of the story. Monsters don't drop gil so you have to sell items or find it in the chests, which are floating spheres (?). All shopping is done online at the save terminals. Some would argue that you don't even NEED to shop through all of cocoon.
Is it linear? Until you reach pulse it's almost exclusively linear. There are some diverging paths for treasure, but you pretty much are heading towards a single goal along a narrow path (that is usually too narrow to avoid enemies). Does it really make sense to be linear? Most of the time yes, but there are a few examples where they COULD have let you do more exploring.
Casting without MP? They completely did away with MP. You can cast all you want as long as you have segments to cast with. Also your HP all come back when you finish the battle and everyone gets CP whether they lived or not, or even if they were not in your actual party when the battle happened. It feels odd to come back to a previous characters story and have 10000 CP waiting for you before you even fight anything, but I'll never turn away free CP.
I enjoyed playing the game. It's highly frustrating at times. It's very nice that when you game over you can restart just before you enter the battle rather than going back to the save point. That would have been a deal breaker if it would have been the case.