I would recommend it for sure!
-story: if you have played some other Fire Emblem game, the story is kinda similar, but in a good way.
-music: the music fits the mood perfectly, my personal favourites are Tiki's theme and 'You may call me Marth'.
-characters: they're all unique in their own ways, and it's really fun to see them talk to each other in the Support, which is definately one of my favourite aspects from the game, the whole marriage system is brilliant!
-gameplay: I can't say more than: perfection. I loved that you can finally use two characters in combat
-difficulty: you can choose between Classic and Newcomer, I recommend selecting Classic, even if you're new, since permanent death is really one of the characteristics of Fire Emblem, and you'll get more attached to the characters and it becomes a lot more 'intense' since if someone dies, he'll be gone foreveeeer! You can also choose between normal/hard/lunatic. I recommend beginning with Classic and Normal.
-graphics: I really, really like the graphics, especially compared to the DS version of Shadow Dragon, the character art, the map and of course the cutscene are all beautiful. They should make a Fire Emblem anime!
-replay value: this game has a great replay value, because of the whole marriage system and permanent death. It also has a lot of extra content, a part of it is free and downloadable through SpotPass.
Overal, this is in my opinion one of the best 3DS games out there. It's also a pretty long game, so it will keep you busy for quite some time