I think it's hard to generalize whether vertical farms are good or bad; efficient or inefficient. It seems that whether it works or not relies very heavily on the locality.

In my part of Ohio, we have lots of farmland -- and plenty of water that just falls out of the sky. We've got reasonably-long, generally-hot days during our growing season and we get some serious crop production done here while it lasts.

The rest of the year? The days are short. It's dark and cold outside; frozen, even. We can't grow crops outside here in the winter.

But vertical farms (eg, fancy greenhouses) can just keep going. With artificial light and/or supplemental heat, they're still producing even in the depths of winter.

Thus, I can go to the grocery store near my house and buy a locally-grown tomato in February. It's expensive to get this done, but the alternatives include paying someone to drive it up here from thousands of miles away or just going without a tomato until after things have warmed up again and stayed that way for awhile.