A focus free lens is a photographic lens whose focal point is fixed at its hyperfocal distance. Rather than having a method of determining the correct focusing distance and setting the lens to that focal point, a focus free lens relies on depth of field to produce acceptably sharp images. Most cameras with focus free lenses also have a relatively small aperture which increases the depth of field. 

The advantage of this is a less complexed design, more so than automatic or manual systems. The system is also effectively automatic; the photographer need not worry about focusing. It can also be more predictable than automatic systems.  

Bottom line: Fixed focus advantage - you don't have to worry about focusing the camera 
Disadvantage - your images are not quite as sharp and you can't focus as closely