While some have said that they don't like the campaigns, I wish to differ. I find them fun, they let you see the lore and backstory of the game, and I for one, like to have some sort of set goals sometimes, and not a total sandbox (which I also like, but to be able to choose is even better).
The book was good because of that, who would have thought that below East Anthys was a huge underground world!? I think the wastelands will give you the chance to show more, like the Imperius one (How about a Calebethon one? I don't mean underground maps, which would still be cool, but sort like if you build a city by one of the entrances, you get a bonus at some resource, or if you build cities at different caves entering the complex, troops can move between them without enemies looking at them!)
I concur with the others, give us some gameplay video, or something! While hearing the details is awesome (what other company let's players talk with the devs?) some footage would be also well recieved, just don't show spoiler things if you don't want, but a gree landscape is hardly spoiler-y 
Hope to hear more soon! FE is looking good!