Please explain the benefits and disadvantages of group guided tours in a foreign country

Hi all, I have no experience with a group guided tour in a foreign country so I thought I would ask the community here. Are there any benefits to an organised group tour that you may not have when travelling with a friend or family member in a foreign country? What may the possible disadvantages be when travelling with a group is there a level of freedom to still explore independently? What may the disadvantages be when travelling with an organised group tour? What countries do you recommend a group tour for in Asia, Europe and the Pacific Islands? What countries do you believe a group is not necessary for?