V-bar are excellent on hills, ice and other hard packed conditions.  They are great in New England with the severe icing conditions.  They are not recommended on pavement since they can damage the surface if the tires begin to spin.  The V-bar is also know as "reinforced" since they extend the life of the chain since you have to wear through the v 
before you begin wearing the cross chain itself.  
*The v is on all cross chain links except the ends links where the cross chain is attached to the side chain.