So I'm going to disagree with nupe1911_md, but based on my limited experience with ortho onc (I rotated as a sub-I on it) it is a very litigious field with poor reimbursement and as a result it generally costs an institution money to have them on staff.
As for the types of cases that we did:
a lot of soft tissue tumors - MFH, liposarcomas, hemangiomas,
rare primary bone tumors, but when they do those cases they are often incredible with extremely interesting reconstructions and prosthesis uses
metastatic bone disease- tough to see cause it was often the presenting symptom for the primary tumor; but once again cool cases
Other things that are good (in my mind):
You have long term relationships with your patients, these often require multiple surgeries and or years of follow-up to watch for recurrence of disease.
You work with patients of many different ages, backgrounds, and personalities.
There are also lots of different types of ortho oncologic diseases and they vary from things with high cure rates to highly fatal, but either way you make a big difference.
It is very academic, intellectual, research driven, and there is a lot of cutting edge technology used.
Hope this helped... and like I said this is based on my limited experience, so don't take my word for it, check it out yourself.