If you have a DS and like FF games than this is a must buy.
This game is realy quite good, and like all FF games it has an immersive story line and great graphics. Though the gameplay graphics may not be revolutionary, the sound and video effects in the various cut scene movies at key points in the game really are.
The gameplay itself is well thought out, and plays a wee little like Tactics for the GBA. Of course it is'nt the same, you'll have the usual complete control over all the characters, and be able to have five characters in your party at once. This isn't much of a hindrance in the game, considering that you'll only have 5 to 6 characters in your roster for a good portion of the game.
There are no random battles in this game, (like FFXII itself,) And to get into battles you'll have to select one of the many missions and side quest's in the game. The battle sequences will take you into a small open map, this is were the similarities between Revenant Wings and Tactics begin and end. Your characters will be able to move to any location on the map at any time, no turned based combat.
As you progress in the game you'll be able to unlock more abilities for your characters and be able to purchase more monster summons from the pacts screen. There is a good number of monsters (espers) to choose from, and as you beat various Esper bosses in the game you will gain the ability to unlock them for your own use.
There are three different levels of Espers, I, II, and III. Level one Espers of course are the weakest and least costly, but will often lead the way in weakening your opponent and serve as low costing fodder. Level II Espers will make up your basic attack force and can be used to take out those which the level ones left behind. Level two's also serve as good defense fr your greater attacking powers, your own characters and level three's. This tactic is probably your best bet. Level three's of course are the titans, and if used effectively can be crucial to your quick victory.
Summoning the Espers themselves is a pretty simple ability. You can summon them from the various summoning platforms on the maps, (warning: sometimes there will be no summoning platforms on the maps and will have to make due with your own characters and your first auto summon, be sure to change your summon list to best suit you in these occasions) Summoning a monster takes up AP, and each individual character has his/her own AP. Once all accumulative AP has been used up you will not be able to summon more espers unless one dies or you capture more platforms to fortify your AP. You can only summon one level III at a time.
Movement outside the battle zone is simple. While outside of the Airship you can either use the D-Pad or the stylus to direct the character to were you want to go. Airship controls are pretty much the same. While in the Airship you can talk to your friends, gain information, and use shops. Eventually there will even be a forge open to you were you will be able to craft your own weapons that can vastly outstrip the normal ones in power.
I won't ruin any of the story for you but as you know, if you've ever played Final Fantasy, that the story line will be fantastic.