If you remember the old Warlords PC game, If you like Bejeweled, or both, like I do, this is a great choice!
The best way to explain the gameplay would be Bejeweled with a versus mode. You clear the standard blocks to charge mana for spells, then cast for various effects, such as clearing all blocks of a color, adding more skull (attack) blocks, or direct damage to the enemy. I advise to use stun as much as you can, as you get an extra turn every time (later on, stomp is nice for this, too). You learn new spells as you level up, and you also collect some pretty neat items throughout the game that add different effects. Early on, the creatures you face are not too bad, but as the story progresses, you will face some pretty tough bosses and enemies that are resistant to some of your spells, that can take a bit of patience to defeat, as well as some strategy adjustments.
More story and deeper cutscenes would have been nice, but there is a lot to do, and this game really sucks you in. A must buy for the PSP.