I think it's looking pretty good. I don't see what you could want from Fire Emblem DLC apart from more chapters, more characters, and high difficulty. I really like that there are looking to be a ton of maps, too. There are over 20 DLC ones so far, aren't there?

My understanding is that each DLC pack is 1) a new character who's unrelated to the main campaign, and who has little interaction with anyone outside of his/her unique DLC, and 2) a map populated with characters appropriate to his/her theme (early on there were only three variations of said map, although the enemies were different).

It's not bad, per se, but I'd have liked something meatier. An imperfect analogy is that this is kind of like DLC for Oblivion, while I'd prefer to pay more for DLC akin to Fallout's.

I agree, but I think you can chalk some of this up to Nintendo being ultra-conservative (what?! That never happens!) and just very gingerly putting one toe in the DLC pond, slowly, before deciding if the water is to their liking.

(My guess is, with returns like this, they'll be buying the beach and putting up a 5-star hotel on it.)

That's probably true. Maybe my analogy will become more accurate as we go on, and Nintendo's Horse Armor will morph into Honest Hearts?

That's an analogy we can work with, but please don't give them any ideas about horse armor.

That was the start of it, but it seems to have become a bit deeper as it went on. The first ones were more of a nod to the past, and more of a fan-service-y approach. There are 5 different gametypes/maps, and each had 3 different groups of enemies on it (so 3 DLCs with the same map, for each of the 5 maps).  Those 15 DLC (5x3) were the first series.

The second series seems to be more original. The first DLC is a simple map and adds 92 (apparently - source is serenesforest) new support conversations between your characters. The second in the second series is a map that has your units reduced to 1hp every time your turn starts. 
The third one in the second series is also more unique, where you defend 5 different NPCs, in different parts of the map.
Then the fourth one (and last to release so far) you seem to have to chase 4 enemies trying to escape from you.

So the first series seems decently interesting, while the second ones seems like it could be a lot of fun.

Edit: Overall, it's more of Intelligent Systems starting out with what they know is going to be accepted, and then trying new stuff.

Huh. I stopped following as religiously after the first ten or so, since it seemed like they'd all be cut from the same cloth. Apparently that was sloppy of me.