Simply described, PSO is a futuristic, somewhat different, but just as challenging, Diablo, except for the XBOX.
When I first played it, I of course noticed the flaws rampant in the game -- not a lot of big things but several little things. The controls take some getting used to, but once you're used to them, it's worth it. The flaw with the controls comes in different forms: Firstly, the camera cannot be pitched or turned in any way. It stays fixed facing the same direction the entire game unless you use the L Trigger to re-fix it behind your character. And it's not isometric view, either; it stays facing forward, so you do have a blind spot. But this is forgivable with the way the environments and battles are set up. Instead, the right control stick (the controls are not interchangeable for lefties) and the d-pad are used to signal chat messages that you have to set in for yourself. The game is useable with an XBOX keyboard, but it's only for chat, as is the exclusive-for-XBOX mic capability.
Another flaw is how much they could have chosen to improve the game, especially graphics- and sound-wise. In Episode 1, the graphics, while not terrible, could have used some serious improvements (especially in the texture area), but more so the mediocre sound. The music, while it in no way gets annoying -- and even plays an ambient role as you progress, sometimes with sounds that make you think there's something behind you -- is fairly bland. It's amazing how I cannot possibly annoyed by the same music of the Pioneer 2 (the game's central hub and "town" for refueling and shopping and quest-taking) so it's not all bad, but the sound effects are few and far between and empty. There is no voice work in the game, except maybe a grunt or something somewhere. A lot of the sound effects in the game sound like stock sound, especially the way the Wolf monsters die, which is a sound I heard playing Banjo-Kazooie. Although, I have heard that playing Episode 2 is almost like playing a different game (graphics-wise) after you get into it a while.
They could have added so much into the game, little things to make the game even better, but I suppose they let lying dogs be, or however the saying goes, since they probably did not want to upset purists, which is pretty much almost the entire crowd for the game.
However, despite all this, the game still manages to be highly addictive. The ability to make a character from twelve different character classes helps (four variations for 3 character classes, Hunter (Fighter), Ranger (Archer), and Force (Wizard)) a lot, because each little different character class has a distinct progression through the game; some start with less HP than TP (the game's "Mana") but soon their HP will fly right by it, while others stay that way throughout the game (unless you uber-modify their gear using the empty slots they may or may not have). You'll find that each character class has a distinct play style; the Hunters run forth and slash their enemies apart while keeping an eye on their health; the Rangers run and gun, playing games with the enemy by dashing around to avoid getting hit; the Force stay back as far as possible and obliterate their enemies from afar using powerful spells.
Note, however, that you cannot just button-mash to get through the game. The game automatically targets the nearest object, whether a box, an item, or an enemy. This is the most frustrating feature of the game, which direly could have used improvement. While this certainly cant get in the way in the game from time to time, once you've gotten used to this unfortunate feature of the game you can learn to play around it, and even (for Force characters) use it to your advantage. Allow me to explain... sometimes a monster will be too far away to hit with a technique (spell), but rather, there will be a box in front of it that you CAN target. In the game, you can use this to your advantage by using and area-of-effect technique (which usually don't come up till later in the game) to hit any monsters near the box. This then destroys the box, and the enemy starts to approach you so you can continue wailing on 'im. Of course, for Hunters and Rangers that cannot use techniques (the androids namely), it can be a little frustrating. But another reason you can't just button-mash is that the game will not allow you to string your attacks into a 3-hit (the game's maximum) combo unless you hit the button at the proper timing. While it may seem frustrating for newbies, it's actually welcome for someone like myself who has grown weary of the usual "jam on the different attack buttons until the enemy is dead" theme ever-more present in Action-RPGs. Hitting the enemy in a specific pattern is a sort of dance that actually makes your attacks FEEL stronger than just "hit weak attack, medium attack, and power attack; yay, the enemy is dead." Stringing attacks properly actually takes some sort of vague semblance to talent! The quests are a bit different than some of the other, older Action-RPGs of its age; most games would let you save your quest's progress, or even save as you go, but PSO allows you only to Save & Quit; if you do not choose this option, your character progress is not saved. When you start up that character file again, any quest you started but did not finish will be restarted. That's not the only thing; dungeons are randomly generated, like Diablo, so when you Save & Quit and restart, the dungeons refill with boxes and monsters and change shape. The only exception to this rule is quests; they are pre-set maps. But that's not the only similarity it holds to the aforementioned classic, Diablo; the whole game's mechanics and setup has a bit of the feel. Going into dungeons alone (on single mode; more on other modes later) to fight swaths of monsters and the like, all similar to Diablo. Your inventory is different; you can only hold 30 different types of items, and only 10 of one type of item, which is very restrictive, but gives a sense of survival, and discourages rushing through in a straight-up blitz through the dungeons; after all, if you could hold 100 healing items, you'd have no reason to go back to town, other than to maybe sell stuff. The ability to set up hotkeys for items and techniques is also a feature from the PlayStation version of Diablo, as in that game there is a certain button to use a certain kind of potion.
A very bad and almost unforgivable feature of this game is that you CANNOT play the game without having an XBOX Live account. Simply put, if you do not have XBOX Live, you cannot play this game, even if you bought it. On top of this, the only way to play the online multiplayer is by paying an EXTRA $10 (US) a month, which it makes no mention of on the box -- only in the lackluster and bare "instruction" manual. It gives you a link to an in-depth online manual, but if you put that link in these days, the website will have no idea what you're talking about. Also, there is an offer inside (if your copy is intact) for a free USB-to-XBOX converter for use of a keyboard (or a mic, I suppose) but the offer expired years ago -- the faults of playing an old game. Speaking of the online game, though, less than 50 people at any given time are playing it online, as the steep monthly price is enough to ward away even some of the most hardcore gamers. While there may be more scattered across the different servers, most of the servers and blocks are empty, except for Server 01, Block 01. And another bad this about playing this game years after its prime is that most gamers you see on there are not legit; most are glitchers and hackers, who open up a character file explicitly for hacking into it and maxing their character out with the most powerful gear in the game, and even giving this gear away to anyone they see. Where the hell is the fun or pride in that?! Seriously, that's like walking out to go hunting, only upon your arrival at the forest, a man approaches you with the head of a 10-point buck on a platter and says, "Good huntin', dude." No sportsmanship or challenge anymore... Despite all this, I (more often than not) play the game alone on Single Mode. You can play the game with friends, however, in Multi Mode, so long as your buddies have their files (on your XBOX or in a portable memory slot) and controllers with them. That I imagine is a lot of fun, if you're all legit. One play style I suggest, however, if that when you start a new file (like I do a lot), take the first quest you see from the Hunter's Guild (the place where you accept all your optional quests), titled Battle Training. If you have no idea how to play this game, the quest will get you started. Then after that, take the Magnitude of Metal quest, and you should be pretty well adjusted to the game and ready to take on the levels alone and in any way you wish.
There are also other fun features of this game, little touches that accentuate its addictiveness, but seriously, why are you still sitting here reading this? If you have XBOX Live and a few bucks to spare, go hunting for this game! I promise you, if you start this game open-mindedly and stick with it till you're used to the controls, you won't be disappointed.