This game is heavily story based, but this is Capcom so parts of it are badly written. But this is the best story I believe they've done so far, so use that as you may. The story revolves around Nilin, a strong female protagonist that seems to be part time MMA fighter and librarian. I'm biased because I actively seek games with characters that aren't the normal deadpan bulky white guys, but I was pleasantly surprised by her character. She's independent and usually on top of things. She also occasionally responds flirtatiously to advances instead of the normal heartless deadpan responses like those in Uncharted, so she takes a spot in the precious few cases of true female characters in AAA titles.
As for the mechanics, it overburdens itself a bit. It has a cool mechanic wherein you scan back and forth over someone's memories finding small things to change so they remember the event different, fundamentally changing their character, but you only do it like 5 times. There's a build-your-own combo mechanic like in God Hand and it's well implemented and allows for variation.