An RPG series with plenty of unique twists, Wild Arms is generally a good series, and Wild Arms 3 is no exception to this stylistic uniqueness. It has as much in common with a Wild West story as it does with a fantasy RPG.
The story follows four characters (each introduced with their own side-story prior to their uniting) who are on a quest to recover a mystical scepter that will restore order and protect the world of Filgaia. The four characters are Virginia, a young girl looking for her father, Gallows, an ex-priest, Clive, a bounty hunter, and Jet, an unprincipled treasure hunter. The story itself is less important than the setting, which contains elements of Western stories contained in the fantasy elements (shooting monsters with sixguns, for example). The setting is pretty distinctive, and is reflected in the music and level design in the game.
The combat system is a regular turn based RPG system, with a few quirks. Firstly, all the characters use guns (or ARMs), which means they need to reload every so often. This is done by using the guard command; while defending, they will reload their guns. In addition to shooting, there are magical abilities and items to use; standard RPG fare, basically. The only other thing notable about the combat system is that it is possible to cancel moves; this wastes a turn, but may prevent you from doing something you don't wish to (such as accidentally using an elemental attack on a creature that heals from those attacks). While exploring, there are some neat tricks as well. Characters can sprint or sneak, depending on the situation, and there are also special abilities like lighting fires or throwing boomerangs that are used for puzzle-solving. Finally, and most importantly in my opinion, characters can avoid random battles with good timing by pressing the circle button when an enemy approaches (signified by an exclamation point over the character's head).
On the world map, places aren't instantly marked; characters need to get clues and information, and then essentially puzzle out where on the map the place is. This is kind of neat, in the sense that the characters are drifters and need to find out where stuff is, but at the same time it's somewhat frustrating because of the random encounters.
The graphics are cel-shaded, and definitely pretty good for their time, but they haven't held up well. Everything seems kind of bland despite the reasonably cool character designs. The sound has a nice Western motif to it, as mentioned, but there isn't any particularly exceptional music, and there's no voice acting at all. In most ways, it's similar to Skies of Arcadia - this was the game that I kept thinking of while I played this. However, it also lacks a lot of things that SoA had.
This was definitely a good game in its time, but unfortunately it hasn't aged very well. If you are a fan of the series, or a hardcore RPG fan, pick it up. But otherwise, at this point, don't bother.