Don't.
If you don't own all the previous 4 that is (so it adds up to a double negative meaning if you do, buy this one too).
This game is the worst FE to reach American shores. It lacks the steps forward that have been implented after the original, and it is far, far simpler and less interesting than the rest.
Buy the 2 GBA ones for your DS. You'll get them for lower price, and both are better (and longer). By far.
And if you own a Wii, get Radiant Dawn and Path of Radiance. They're bloody brilliant (but harder to get your hands on).
For your first purchase, go with FE7 (just called Fire Emblem for GBA in Americas/Others). It introduces you to the series in a great way, and is the second best game in the series (Radiant Dawn is better, but it's a sequel, so you should play 9 first, and 9 isn't as good as 7 or 10).
If you never played a Fire Emblem, Do Not get this game, get an other Fire Emblem.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS







