Certainly not for everybody, but fans of 2D RPGs and fans of visual novels will love this game.
Ar Tonelico follows the story of a young knight, Lyner, as he sets out to search for a crystal called a Hymn Crystal to save his homeland, Platina, from a virus (enemies, not disease) attack. While the story might start out pretty slow, it quickly starts to pick up, and doesn't really let up at all as you progress through the game. The story I believe is told really well, and since there are actually two paths you can take during the main course of the game, it just expands the story a little more so you can fully understand it.
As I already pointed out, this game is in 2D, whereas the world is a 3D interface. I really do think the sprites look really well detailed, and are probably some of the best sprites that I've seen in a game. While some of the animations aren't there (if you run away, your Reyvateil simply jumps backwards without any movement), it's hardly anything to nitpick at. The environments, on the other hand, are a bit repetitive. Though they may look nice, the same kinds of scenery are used all too much for the towns and dungeons in the game.
The soundtrack to the game is a good one. There's a lot of tracks in the game that will remind you of either the Atelier Iris games (if you played them), or of an old RPG back from the SNES days. There's something in the soundtrack that everyone can like, though I can do without the rapping in a couple of the battle themes.
The voice acting is good for the most part, but it's not on the same level as the Digital Devil Saga games. The majority of the voices do fit the characters, and the emotions are done pretty well, but at some part of the games, I felt that the VA's could've done a better job.
Ar Tonelico is a turn based RPG. At the top of the screen, you have portraits of your characters and enemies with a blue bar next to them. The blue bar represents when you can take your action. Once the bar is filled, that enemy or characters turn to act comes, and you can select your action to take. After it, your portrait is moved back a specific number of spaces, depending on the equipment you have on and the characters agility.
During battles, you have your front line characters, and your Reyvateil at the back singing their songs. Once they start singing, a Burst gauge will appear, which is basically telling you how strong the song is getting. Singing a song will consume MP for a Reyvateil, and once their MP reaches 0, the song will activate automatically. MP Regeneration for the Reyvateil is quick, so you don't have to wait long to start up your next song. However, Reyvateils are physically weak in the defense area, and therefore need proection if an enemy targets them. You get a warning if an enemy is going to target your Reyvateil, in which you respond with guarding them with one, two, or three characters, depending on how many rings appear around the Reyvateil.
Also that's something a bit fresh is the Harmonic Gauge, which is at the bottom of the screen. There are two bars: a Blue bar, and a Pink bar. The blue bar represents the "excitement" of your party. Whenever one of your front line characters attacks, the blue bar will rise. Using skills will raise the blue bar even further. The pink bar raises on its own even if the Reyvateil isn't singing. Once the blue and pink bars touch, your Harmonics will gain 1 Level. You can do this until it reaches Level 4. The Harmonic Gauge is basically there for you to gain more items in battle, and to make your physical attacks more powerful. You can gain up to 4 items per battle, with the Grade 4 items generally being rare items late into the game.
What I liked most about the game was the indepth character interaction you can do with your Reyvateil, or singers. Basically you have Reyvateils that will get close to you in the game, and they normally don't tell you much about them. In order to learn more about them, their fears, embarrassments, happy times, or any other feelings, you need to Dive into that Reyvateil and make your way through their Cosmosphere, helping them regain confidence or help them recover from a fear they've had for awhile. As you venture deeper, you'll witness all the personalities the Reyvateil has towards you and the other characters. In other words, it's sort of like a novel. It helps you learn more about that Reyvateil and what they think of the other characters. This kind of character interaction needs to be in a lot more RPGs, if not all games. You can also expect a lot of sexual innuendo and a tiny bit of bondage in the game. Though it's not all over the game, it's pretty noticeable during certain scenes and scenarios.
Aside from the Diving feature of the game, there's Item Synthesis you can do. Basically you have to find ingredients to make certain items, such as Key Items, Ingredients, Useable Items, or Equipment. Some recipes are easy to make, and easy to come by, whereas other recipes pit you with items that are hard to find, or you don't even have yet and have to search for another recipe to make the current one. The Item Synthesis itself is pretty expansive, and there are plenty of items to make.
If you're into hard RPGs, you'll be very disappointed in this game, as Ar Tonelico: Melody of Elemia is really really easy. I suppose this can be good for an RPG newbie, but seasoned RPG Vets will probably find no challenge in this game whatsoever, as the majority of normal fights and boss fights are pushovers, and considering your Reyvateil can heal you every few seconds with certain songs, the challenge is pretty much sucked away from the game.
Thankfully, though, there is some replay value in the game, as there are 7 different endings, and two paths to take during the main game. You can get 4 different endings with two of the Reyvateils, Aurica and Misha, depending on which route you take. There are a couple of other endings in which I won't say, as that will spoil some of the fun for you, but the replay value is there for you if you're curious about the endings and different paths in the game.
All in all, Ar Tonelico, while far from perfect, is a perfect fit into the 2D RPGs, and if this is really the last 2D RPG that we'll see on any console ever again, then I'm glad this game is the final one we'll ever see, as it makes the genre go out with a bang.