WA 3 suffers from dated RPG mechanics and some design flaws but is saved by it's unique setting and enjoyable plot.
As mentioned the Wild ARMs series takes place on the ruined world of Filgaia. Although if you haven't played any other games from the series you won't find yourself lost as there is no real connection to the previous games aside from the world itself. Some time ago events caused the planet to slowly decay leaving much of it barren wasteland. The story focuses on a party of adventurers after they meet up in at the beginning of the game on the same train. The way the game starts off is particularly of note as it splits the prologue into four parts in which you play as each member of your party separately allowing you to see part of why they are all on the same train. Your introduced to a naive but kind young woman named Virginia, a young treasure hunter named Jet, a shaman on the run from his heritage named Gallows, and a middle aged archaeologist named Clive. After they meet up the end up embarking on the usual adventure that escalates into them saving the world. While it's not the most original story it's handled very well and manages to be enjoyable from start to finish. It's good stuff, even if you have played through better stories. Said story is progressed through frequent in game cut scenes and does so exclusively through text. Those of you used to listening to voice acting might find it a shock but you'll find the story well written. The only problem with WA 3's text story is that during the opening, one particular scene toward the end, and the ending you don't have any control over the dialog. For the rest of the game you have to press the X button to advance the dialog which works out nicely allowing you time to read at your leisure. During the three mentioned areas the game advances the dialog for you and does so much too fast. If your not a speedy reader you'll miss out on several parts of some fairly important conversations. This is really annoying and strange since it only crops up in those three sections of the story.
From a gameplay standpoint Wild ARMs 3 is rather dated. It uses a turn based system for combat but does so in ways that still keep it interesting. Rather then using MP for abilities and spells characters gain force points (FP) by attacking with their respective weapons. These FP can then be used to cast magic or make use of any of the characters special abilities. While using abilities depletes your FP reserves magic does not, so as long as you have enough FP to cast a certain spell you can do so over and over without a second thought. This is a nice change from all the RPGs that force you to tactically use magic due to the restrictions of MP. To add to the nostalgia (or frustration) factor Wild ARMs uses the ancient RPG mechanic of random encounters. Although the game does feature the ability to skip a certain number of them and if your powerful enough you can skip all encounters in an area period which is a great blessing. Aside from combat there is a good emphasis on puzzle solving throughout the dungeons spread across Filgaia. Each of your party members has unique tools that they can use in the field which will have you switching back and forth between them. For the most part it's fun as opposed to simply slogging through waves of monsters in every dungeon. When your not engaged in the story there are a number of side quests you can take on ranging from the usual optional bosses, collesium, and multi floor dungeon to a series of hidden puzzles and thwarting an alien invasion. If your not the kind of person that likes to wander around and talk to everyone it can be very easy to miss out on most of the side quests but you'll likely stumble across at least some of them when you find yourself stuck and looking for directions to advance the story.
While Wild ARMs 3 is generally a good game some of it's gameplay mechanics serve to prevent it from becoming a great game. The main issue being the overworld map. To find anything in the barren wastes of Filgaia somebody has to give you directions. As you walk around the world map you press the square button to send out search waves and (if somebody has mentioned the locale) it will then appear for you to enter. You can stand over a new town sending out search waves but you won't be able to find it until somebody actually tells you it's there. While it's a neat idea in concept it just becomes annoying in practice as you walk around pressing the square button every few steps till you find what your looking for. Not to mention having to talk to everyone till you find the one person that has actual directions to where you want to go. Other detractors in fun factor would be the game's difficulty, if you take some time to level grind or do some side questing combat can become rather easy, the same can be said for most of the games puzzles. The only puzzles that most players will have trouble with are the ones that don't give you any real idea of what your supposed to do to solve them. There are also several occasions where you'll be left scratching your head, wondering where your supposed to go next to advance the story. Your only option being to go from town to town talking to everyone with each of your characters till you find the one npc that tells you the location of where you need to be going next.
Being a Playstation 2 game from 2002 one shouldn't expect Wild ARMs 3 to look amazing by today's standards. None the less, the game uses a cel shading style the tries to emulate the anime opening and character art. It works well and has actually aged a lot better then a lot of other early PS2 titles. The western feel of the world comes across well in the games various dusty towns and it's sprawling desert wastelands. It's original and once you play it you might wonder why there haven't been more RPGs that make use of a western setting. The same can be said about the games audio, the soundtrack features a surprising amount of whistling to complement the western motif. The song that plays during the opening cinematic as well as the end credits will likely get stuck in your head after but the rest of it is mostly forgettable but not annoying.
If you can get past the games dated RPG mechanics as well as some of it's design flaws there is a lot of fun to be had here. Even with all it's issues the story should make up for a lot of the games faults. If your fond of older RPGs then you'll likely have a good time while it lasts.