shadowofchaos725:

• Hoshido has a world map.
• Nohr has more complex maps. Besides the usual “defeat all of the enemies”/“defeat the general” maps, there will also be suppression, breakthroughs, defending bases, turn restrictions, amongst others. There are lots of map gimmicks. (We’ve already seen dragon’s vein.)
• Both versions of the game contain the same characters. You’ll be shown different aspects of their personalities in accordance to the route you select.
• The downloadable version does not contain both sides. It does not lock the other route when you select one. You pay to receive everything up until chapter five, and once you make a decision, you will have to download everything from chapters six, onward, for the respectful route. The second download is free because you have already paid. If you want to try the alternative version, you have to buy DLC in the same way those with physical copies will.
• You can also save directly to your 3DS system (versus the cartridge).
• If you decide to buy the DLC, you can load your chapter 5 data and continue from that instead of starting from the beginning. Of course, you can restart if you’d like to.
• You’ll be able to experience an entire story by only playing one route. The other is a completely different story.
• The third path is in the middle of Hoshido and Nohr in terms of difficulty. People who began with Hoshido should still be able to complete the third path.
• You’ll be able to lower the difficulty in the middle of the game if you find Nohr too hard.  
• You’ll still be able to connect with people who play the alternative version. (Probably means you can streetpass someone with Nohr despite playing Hoshido, and vice versa.) There will be various perks for connecting with other players.
• The developers wanted to make a game which took the Arran/Samson choice from FE1 to its extreme.
• The two versions share about 1/6 of the story, the remaining 5/6 plays out differently depending on the version.
  

So yeah, screw everyone that says “Oh damn, IS is going for a cash grab by selling us half a game and forcing us to pay for the other half!”

That “half a game” is just as long as Awakening. So it kind of makes sense to pay a little more for the “full experience” if that “full experience” is double Awakening’s content.