Fundamentally Chaos Rings embodies a lot of what I'd like to see become common place for games on the App Store: Great production values, deep engrossing gameplay while still being easy to pick up/put down quickly for on-the-go gaming, and overall just a lot of fun to play. As far as price is concerned, I don't think it is a lot to ask considering the level of quality. If you compare Chaos Rings to your average iPad game...well, there is no comparison.
The story is relatively interesting and well paced, although somewhat sparse and at times melodramatic. As long as you aren't expecting a tale of epic proportions it should keep you engaged through out the course of the game.
The graphics are truly in a league of their own when it comes to iDevice gaming. From the quality of artwork itself to the technical quality of the graphics it's all gorgeous to look at. Clearly a lot of time was spent on the look of this game.
As with most RPGs, combat is where you will be spending the majority of your time with this game. This is where Chaos Rings both shines and starts to crumble. First the positive, the combat system is deceptively deep for an RPG. At the beginning of each turn you must first decide if you want to execute a solo attack, or paired attack. Solo attacks do less damage, but enemy attacks target one character. Paired attacks do considerably more damage, but enemy attacks target both of your characters. Also, when using the paired method in combination with healing or stat boosting spells/items both characters receive the effects.
Magic is handled through learned "Genes". As you defeat enemies in combat you will sometime receive their Genes. You can equip these genes to use the spells of the enemies you defeat. These spells run the gamut of typical RPGs spells including everything from healing, stat bolstering, damaging, etc. When using attack spells they will typically imbue upon you their element. This means when using a fire element spell your elemental color will turn red, making you susceptible to spells of the opposite element. Likewise, if an enemy using a particular spell against you, you can blast him with a spell of the opposite element for extra damage.
All of this highlights the depth of combat in Chaos Rings, the problem is that later in the game almost none of it matters. Somewhere around the midpoint of your first play through you will most likely have acquired several genes that passively boost your physical attacks. You stack up a few of these genes on one character and suddenly you get one hit kills on almost every non-boss encounter, and bosses typically go down in less than 10 turns. Not only is there no strategy required, but no challenge as well. In fact you will almost certainly find that the first half of the game to be considerably more challenging than the second. This is a disappointment because even the high level areas are relatively easy and more importantly because the pieces are in place for the combat to be both strategic and challenging but because a few skills really the balance is completely ruined. I suppose you could choose not to use equip the genes that have these skills at all, but then you would lose out on all the other skills that come with the gene.
Even with the issue with the difficulty I'd still highly recommend Chaos Rings because it is a lot of fun, and overall worth the admission price.
One last note about the iPhone Vs iPad versions. If you own the iPhone version, the iPad version is definitely not worth getting. If you own an iPad and are debating which version to get, I guess I'd give a slight edge to the iPad version, but not by much. Not only is it a direct port with no added content or features, but the one thing that was upgraded (graphics) wasn't even done properly. As many have noted here, the backgrounds are almost all (if not all) taken directly from the iPhone version. Early on in the game there is a scene where a character is holding a sword, you will see that the shaft of the sword appears to have updated graphics, but the blade is the blocky iPhone version. That being said, the increased resolution does look really nice where it was done properly.
Anyway, that is my review of Chaos Rings, hope it helps someone make a somewhat more informed decision.