Legally, and from a safety perspective, very very problematic.
There is no formal certification basis that can be used to clear a UAV (Unmanned Aeriel Vehicle) for operation VFR in the open FIR. To the best of my knowledge, these systems contain no form of TCAS, auto-evasion, or auto-destruction system. They *might* contain a transponder, but aren't legally required to.
They almost certainly will however be operated remotely in line of sight from an operator on the ground.
But if he doesn't see you, and the UAV is being operated in unrestricted airspace - you're on your own laddie! Pray that they'll have the sense to always operate them either at low level within a connurbation, or within a NOTAMed TRA.
I doubt you'll hear anything officially, but unofficially I've heard that CAA are scared to death of what various police forces are doing with these things, and seem to be toothless to bring them under any formal control.
G