3) The Cost
Now these tours can be extremely expensive or great value for money depending on your comfort levels. I chose the mid range tours which were majority of our nights in hostels and occasionally a upgrade to hotels. All the hostels we stayed in were all of the highest quality and would definitely recommend them all. However if you would prefer a bit more comfort and luxuries, they do have hotel based tours available. Although if you are a real budget traveller and don't mind compromising comfort then tent only tours are available and are extremely great value for money.
Personally I think tours are great value for money. Of course it may be slightly cheaper to book your own transport, hotels etc, generally it isn't worth the hassle. When you look at what is included in your package it is actually quite cheap. Usually each package will include all accommodation, majority of meals, transport tickets occasionally, some tours and sightseeing, and the invaluable knowledge of a local guide.