Keep It Classic
It's simple. Fire Emblem Awakening is a must own game for the 3DS. It takes everything about the series you love and just makes it better. I'm no expert at Fire Emblem but I can't imagine any previous game nailing it better than this.
The first thing you will notice is that the graphics are outstanding. The 3D is used to perfection in cut scenes and the models are beautiful. During the combat scenes you can even control the camera, not a big deal but still very nice. Everything looks very crisp and even the units on the map are easily recognizable to their class.
The controls are intuitive and work the exact way you would want them to. Selecting a character will highlight there movement area, attack area, and casting area for healers. Tapping the X button will display danger zones where your characters will be vulnerable to attack. A feature so useful that I keep it on at all times.
Best of all is the content to this game. The story is amazing, especially the side parts where you build relationships between characters, sometimes even to the point of marriage. Their conversations are well written and you will be dying to get to the next bit before long. It smacks of Persona's Social Links and it is just as well done. Streetpass is used effectively as you can pick up opponents entire armies to duel with, purchase their equipment, or recruit. And then there is the DLC. Loads and Loads of DLC. I personally have not investigated it (far too much money and time) but it is there for those that want it.
There is one thing to be said about Fire Emblem Awakening and that is the difficult slider. You can play on the Classic mode (Permanent Death when a character dies) or casual (characters return after death once the map is completed). The intent is to make the game more accessible for casual players but it feels strange and far too easy on casual. Classic gives you a real sense of strategy and urgency in the game and makes you play in ways you wouldn't always think of doing. Casual lets you fling your army at a wall of enemies without any care. If you want the true experience with this game, Keep it Classic.