I think the best word to describe Valkyrie Profile is "unique." You're unlikely to play another RPG like it and both sequels to the game (arguably both prequels) don't play anything like it or each other.
The game follows the story of a valkyrie named Lenneth and her mission to recruit warriors for Odin's war against the Vanir and the coming of Ragnarok. The game borrows heavily from Norse mythology and Norse mythology buffs might appreciate this or find it blasphemous in its inaccuracies and liberties that it takes. The game is divided into eight chapters with each chapter having so many periods that the player can spend to perform certain actions. This is essentially a countdown to Ragnarok. At the start of each chapter you'll usually (it's in your best interests) to spend a few periods performing Spiritual Concentration in order to reveal new locations to visit. Visiting any location will use up a period or two but there are more than enough periods in each chapter to go everywhere. So you don't really need to worry about it like it's some sort of time limit or something. One thing to note is that not every playthrough will have the exact same locations show up in the same order or within the same chapter as there is a level of randomisation to the order of some events.
What you'll actually do in the game is essentially what Lenneth has been tasked with: recruit warriors, train them up and send them to Valhalla to fight in the war. Certain locations will trigger cutscenes where you will witness the last moments of a party member's life and then their introduction to Lenneth as she recruits them. You'll then gain a new party member. Other locations will simply be towns where Lenneth disguises herself as a human and walks around talking to them. Finally, there are the dungeons where you will engage in combat. A lot of combat. Party members level up as they survive combat and you'll also gain group experience to spend on any party member. As they level up they will also get customisation points to spend on learning skills or the like to customise them. Valkyrie Profile is interesting in how it wants you to spend time levelling party members but then get rid of them. You'll have to send party members to Valhalla and the better they are (level, gear ect) the better they will perform in the war effort and the more Odin and Freya (a servant of Odin) will be pleased. So you'll want a dedicated team of your own to survive the game with but you'll also need to be substituting in new members so they can be trained for the war. And you can't just send any old chum to Valhalla (well, for the most part you actually can) as Freya will inform you of what type of warrior they need at moment and giving them a strong archer when they need mages won't please them as much as it might have if they had needed archers. Giving away party members that you have invested time in and gotten used to might be big turn off for some people and I was initially a bit bummed about the idea but I think it works very well here.
At the end of each chapter Freya will give you an update on the war and a performance review. Perform poorly enough and the game will end prematurely as you are essentially fired. The better you perform the better you will be rewarded. This does unfortunately mean there's somewhat of a snowball effect; if you perform poorly early on you'll find it hard to do well later on. One thing to note is that there are no shops in Valkyrie Profile, all items must be procured from dungeons, enemies or transmuted by spending materialisation points. Basically you have a 'shop' of sort where you can buy and sell items with materialisation points in your camp menu but for story and setting purposes it's not a shop. Materialisation points are awarded at the start of each chapter based on your performance thus far.
Most of the story in Valkyrie Profile is told through the brutal 45 minute opening scene and the A rank ending. Normal play will almost definitely never get you the A rank ending and instead you'll get the B rank ending. There is a third C rank ending but that's essentially getting fired for sucking. So this is definitely a case of "guide dang it." There are, as I mentioned earlier, cutscenes when you recruit party members and there will usually be some sort of brief conversation between Lenneth and the boss of a dungeon but for the most part these are irrelevant to the actual 'plot' of the game. I'd recommend playing the game once through with no guide and then a second time following a guide for the A ending. The game has three difficulty settings (easy, medium and hard) and the A rank ending is only available on medium and hard. The difficulty settings actually affect what dungeons and locations are available to the player, not just the difficulty of combat. I'd recommend your first playthrough on normal and second on hard as you'll be able to experience every dungeon then. There's also a bonus dungeon that you can unlock once you finish the game but you won't be able to access all of it unless your file has items that are only obtained in hard mode. (Again, use a guide.)
Right now I'll talk about the music, it's Motoi Sakuraba and if you enjoyed his work in Golden Sun, the Tales of games or Star Ocean then you should enjoy it here. Valkyrie Profile is definitely one of his better works in my opinion. Practically every dungeon has its own track and there are quite a few battle tracks as well for various bosses. The voice acting in this game is... poor. Some of it is nice but a lot of it is pretty bad stuff. You'll be listening to the same lines in combat a lot as characters cry out their special attacks.
Right, combat. Combat is 'turn based' in that you and the enemy teams will take turns beating the crap out of each other. One thing to note is that Lenneth must normally -always- be in your party as she is essentially materialising the party and if she is defeated you'll have to bring her back quickly (three turns) or it's game over. You are allowed to have up to four party members take part in combat at once and each will be assigned a location that correlates to a button on the controller. Once you chosen to attack pressing the corresponding button will tell that character to attack and depending on the weapon they are using each character has a few attacks that they can perform varying in damage, timing, hit gauge and hitbox. Mages will cast their assigned spell if possible. Your attacks will possibly knock an enemy around a bit and if you're not careful you can miss an attack as one character knocks the enemy up and another attacks at the same time and hits the air underneath. Aside from doing more damage (and preventing the enemy from dodging or blocking) it's beneficial to try and land all of your hits in a combo as each hit will build up the hit gauge by a varying amount and if you manage to get that gauge to 100 you can then perform a special attack. Each character that hit the enemy will have a chance to use their Purify Weird Soul attack. This attack is unique to each character (exception are mages where it will depend on the spell) and if this raises the hit gauge to 100 again then a different character can use their Purify Weird Soul attack. Each subsequent Purify Weird Soul attack will have a penalty to the hit gauge so it's important to know what order to use them in. The amount of hit gauge that you can build up with a character and how easily they combo into the moves of your other characters is an important consideration when picking what party members you want. When hit by a combo enemies will also drop different gems that add to experience, add to the hit gauge and reduce CT. The chance of each gem depends on where and how the enemy is being hit. (Juggled in the air, beaten on the ground ect.) CT is basically a cool down for characters to use items, magic and their Purify Weird Soul attacks. It's important to not be overeager when it comes to using Purify Weird Soul attacks as everyone might have too much CT accumulated when you really need to heal or such.
Outside of combat you'll run around towns and dungeons in a sidescrolling fashion. In dungeons (or when Lenneth is not disguised as a human) you're able to slash your sword and shoot out magic crystals. Slashing your sword will break certain objects or engage an enemy in combat giving you an advantage. If you run into an enemy normally they'll get an advantage. The crystals you can shoot out will freeze enemies and create platforms for you to jump on. These platforms can be created on walls, floors and ceilings and adding more crystals to them will increase their size up to a limit. Exceed that limit and the crystal will shatter and release some dust that you can use as a temporary platform to jump off. There's some tricky platforming and puzzles to be solved in the dungeons and I found the gameplay outside of combat and combat itself very enjoyable. Some of the dungeons can be rather confusing but you are able to consult a dungeon map that is created as you explore.
Valkyrie Profile is definitely a unique game and I'd strongly recommend checking it out as you're not likely to play anything else like it. Aside from the original Playstation release there's an enhanced port for the PSP called Valkyrie Profile: Lenneth that features some fancy CGI cutscenes but is more or less the same game. It's a bit light on the story and basically requires a guide to get the 'true' ending and 80% of the story is contained in that ending but if you're willing to play RPGs for something other than story (and I hope you are) then you should hopefully find this an enjoyable and unique experience.