Looks interesting. I'd consider them for my errands and short hop riding. Considering the weight of my puncture resistant tires and goop-filled tubes, a well designed solid tire probably wouldn't be any more sluggish.

The main advantage a pneumatic tire/tube setup might continue to offer may be the ability to adjust pressure for different rider weights and surfaces. I like being able to reduce pressure to around 50-60 psi for gravel and grass, and 70-80 psi for smooth roads.