I am neither a Realtor nor a roofer; however, as a home inspector, I would be more concerned with the number of times this roof has been patched.  Repairs like this are typically stop-gap measures for a specific reason, e.g. leaking.  While there are several different types of roofing here, a professional roofer would be better suited to access the longevity of this roof and estimate the cost of recommended repair/replacement procedures. This is clearly beyond the expertise of most home inspectors or Realtors.