Just to sum up a bit of what I've seen (while trying not to spoil events):
-Load times are a bit long (I didn't keep count of the videos I've seen for this, but it seems longer than Symphonia/Vesperia's, but a bit shorter than Abyss')
-The monster system doesn't seem that bad. I've seen a lot of people making use of them too.
-Animations are very nice and add a lot to the game's cutscenes.
-I've heard the game was about 30 hours. Now, mind you, this is from people that blew through the story. I'm guessing it's the usual 40 or 50 the series usually has if you take your time.
-Seems to be a lot of minigames and sidequests. Marta even gets a "pettanko" (flat-chested) title. :lol
-Along with the sidequests, seems a fair number of titles are also there.
-Controls take a bit of getting used to, but it seems to be pretty simple.
-A lot of people find the new characters pretty enjoyable.
-Story's actually pretty serious and doesn't seem to "disgrace" the previous game.
-Emil's pretty fun to use (though from what I've seen of the beginning of the game things start out pretty slow).
-There's a lot of skits and Tenebrae's apparently pretty funny.
-Item synthesis is really useful.
-There's a lot of remixed versions of old tracks, but they're good.
Though I guess a lot of this could've just been figured out by seeing videos, but I guess a lot of them had spoilers.
I don't think anyone's found any costumes or a cameo battle yet, but now that a few people (mostly those that got the game early) have finished the game, I'm pretty sure people are searching the game for all the various sidequests. So we'll probably know if any of that's here pretty soon.
I also haven't seen any animated cutscenes, no idea if no one's posting them or they're all ingame stuff, but the animation and the important cutscenes moving automatically (no need to press any buttons and all that) seems to make up for it at least.
Basically, from what I've seen, it's at least a pretty solid game overall.