They book your accommodations, set up your itinerary and take care of all of your transportation requirements. All that's left to do is sit back and enjoy your trip. For these reasons, budgeting for a group tour is much easier than going on your own because you will pay all of your money in advance for virtually every expense you come across. Tour organizers can keep the prices somewhat lower for their customers by getting groups rates on everything they do and working with the same organizations for every tour. However, traveling within an organized tour is not for everyone.
Some travelers find packaged tours to be very rigid and overly structured.
You don't have the option of staying in one place for a longer time period just because you would like to explore more. When the bus pulls out, you've got to be on it. Your itinerary is pre-planned so there are no opportunities to spontaneously change directions. The most important drawback of tour groups is the fact that they have a tendency to stay isolated from the authenticity of the local people and their culture. Traveling in a group of ten or twenty people, you have very little chance of immersing yourself in the ways of the locals.