Unlike other FinalFantasy games, it is a third/first-person shooter. (Both modes are available and can be switched between.) The designer was apparently a big fan of games like MedalOfHonor?. Like many action/adventure games, play is divided into a series of missions with several goals to achieve. Performance (e.g. accuracy, kills, goal achievement) is rated at the end of the mission, and nets you experience points. You have the option of converting the XP to money in order to buy gun upgrades. If you die in the middle of a mission, your performance up to that point is rated and you get XP based on it, so dying isn't completely pointless.
In addition to Vincent, Cait Sith/Reeves? shows up a lot. There's a section where you play as Cait Sith, who can't really attack; it's a stealth mission. The other FinalFantasySeven main characters appear briefly, but decide to leave the main assault to Vincent. There are plenty of flashbacks showing more about the relationships between Hojo, Lucrezia, and Vincent.
The plot is kind of strange, although maybe not that strange considering the rest of the series. Recurring villains include "Azul the Cerulean" and "Rosso the Crimson", i.e. "Blue the Blue" and "Red the Red". Some of the things they did to Vincent's backstory are very weird.