Yes, a new Decree that has been approved on the 15th of May 2015 which forms an amendment on the previous Decree on free choice in healthcare and states that you have the right to choose any medical centre, GP or any hospital or specialist within the Autonomous Region of Valencia. No longer restricted to the immediate region of the town where you are registered on the padrón. If for your job or family circumstances a medical centre outside the region would be more convenient, you are allowed to register there as well.
You can even choose the nurse you want to assist you at the medical centre of your choice.
When you request a change of GP, the relevant authorities must respond within 15 days, but whether your request can be granted will depend on the amount of patients already listed for that specific GP.