Strong, certainly, but fugly as well. Perhaps I'd like it better if it were mostly covered with dirt. I just don't find the shape appealing, or rather I don't find the shape appealing from the outside. The indoor space, however, is another thing entirely. I've seen some spectacular examples of dome home interiors.

That seems odd to me, because I love the way my Eureka K2-XT looks...

That's just my opinion, of course.

As for energy efficiency, you can make just about any type of structure energy efficient if you're an intelligent builder.

On a side-note, creating concrete expends a lot of energy. So, if you're worried about total impact of building a home it might not be the best option, but if you're only worried about the bills it's not so bad.

Of all the alternative types of housing out there, I like the partially underground/earth berm types the most though I have to admit that quite a few of them can be ugly as well. Earthships as one particular example of this type of house seem like a great idea to me, but they're relatively new as a concept, and there are some horror stories out there to rival the successes.

I also like the idea of rammed earth homes.

What angle (pardon the pun) in particular are you looking to discuss, MoBOB?