overall, i'd say it played like a cross between Stand Alone Complex and Devil May Cry. there's a little switching it up, like in SAC, and the hidden target thing was definitely SAC style. unfortunately, the melee attacks are a little limited, and the difficulty levels of the game seem to depend almost entirely upon the way you customize your weapons (and, therefore, how thorough you are in exploring). i mean, you'd be trucking along just fine, then hit a boss and suddenly have HUGE problems (for me, this was Rosso and Azul). i discovered a little later in the game that this is mostly linked to the player's choices about XP vs. Gil and customization.
for instance, there are certain enemies that can really only be handled with magic, and i had never leveled up my Materia boosting items for my guns, so those fights were excruciating for me. but i'd turned Cerberus into the S Cerberus Zero, had a Faerie Long Barrel and an Auto Reloader, and it turned out that i could outfire Nero in the first fight with him (i mean, holy s***, i was firing faster than in the movie!). the Hard difficulty setting is no big step up, either, and the Very Hard difficulty setting lets you keep your customized guns; but the extra missions you can play after the main game are painful so far -- you get no items other than what you find in the mission, and i think Vincent's stats are Level 1 (no clue; all i know is that i got in there and i was like "where the hell are all my HP?!
"), but you get to keep your custom guns. i've only made it to the 7th one i think.
the game was surprisingly short, but with the way the pacing was set up, it didn't seem that short; it seemed like it was about the right length. since you kinda need to replay the hell out of the maps to find all the hidden targets, i'd say it's not too bad. some hidden targets (like the damn cactuars) are awful, and some hidden targets just require you to turn and look at a certain time. i've only found like 7 of the ones in the first chapter, and it looks like there's around 30. T~T
yes, the pacing is really as painful as faide says -- there are times where its fight two normal soldiers, cut scene, walk around the corner, cut scene, fight half a boss, cut scene. but the movies are just sooooooo beautiful (especially the last few few before the end credits and the VERY last movie <3)... even the normal cut scenes were pretty cool, and you have the option of skipping them (a la FFX-2, hurray!), so it's not all that bad.
story-wise, it was great (in my opinion, anyway). i even managed to like Lucrecia by the end (it was really sweet, and they got a good actress for her). and omg Turk!Vincent is so cute and stringy and young. XD he looks like he must be about 17, and definitely a loser (but a cute loser, so i can't say i mind too much). and is it just me, or does Cerberus seem a lot bigger in Advent Children? *shrug* oh well.
but that's enough from me; i have to pack up all my crap so i can move back into the dorms, and then i can get back to hunting down those hidden targets!