Valkyrie Profile: Covenant of the Plume is an excellent, if overlooked, little gem on the Nintendo DS. And yes, it's a tactical RPG.
Gameplay-wise, it has interesting aspects, like the fact that your characters can all gang up on a single enemy, and you decide the order of attacks, which can lead to some interesting combos. Air combos increase experience gained, while ground combos have the potential for most damage (Enemies can do this too, which can be a pain)
There are plenty of ways to micromanage your characters: "tactics" are abilities your characters can perform during movement (you can acquire these, and permanently give them to basically any character), "techniques" are abilities automatically activated in battle (they work like the "tactics", but they have more limitations). You can also change the character's default order of attacks (useful for combos) and the usual equipment. There's also limited items/money, which is a difficulty I don't mind in SRPGs.
Finally, there's a gameplay aspect that ties with the plot: in each map, you must collect a certain amount of "sin". You can do this by "overkilling" your enemies a.k.a. dealing huge damage on them after they're dead, or by permanently killing off one of your own party members. Completing the sin quota nets you the best items, and if you did this by sacrificing a party member, the main character also gains an incredibly useful tactic. Underachieving this quota basically forces you to sacrifice a character in the next map you play.
And like I said, it ties in with the plot. The main character made a pact with the Devil in a quest for revenge. The story is divided into chapters, and there are always 3 available paths in each chapter (usually the same conflict in a different perspective) and 3 available endings. The plot is nothing too long or epic, but it's excellent, thanks in part to the great translation.
Anyway, you can find it on ebay for less than 20€ (I never saw it in stores), and it's definitely worth it.