Sigh, if this guy had an actual 3D printer he would realize those doors and windows are a no-go :-) More seriously, there are unsolved issues in printing unsupported structures, the current best solution is a second 'support' material that can be dissolved/blown away once the part is completed but that rules out voids which are part of what you hope to make with this sort of thing.
Also as others point out this is just the frame (and if you do the robotic crane thing you can add a roof. You might also be able to use your robotic crane to do joists for overhangs but the finish suffers as your joist material is exposed on the underside.
No doubt solvable problems but they take away from some of the 'magicalness' of fused deposition printing. Stereo lithography where the part is neutrally bouyant in the construction fluid doesn't have those issues but it has other issues associated with strength and material choices that can be laser activated.
For now doing a concrete lay-up would be pretty killer but building the forms on site isn't that hard and in both cases you need to transport the concrete at the last minute.
Bottom line I think the stuff that BluHomes [1] is doing is much more creative than trying to do this with 3D printing.
[1] http://www.bluhomes.com/