So for my program it requires that you complete all the normal nursing pre-reqs have a bachelor's in any field, and they prefer some nursing related work experience. The master's is to study to become a Clinical Nurse Leader - see the AACN for description on this certification/ job. Its a certification that I will qualify to take the test for after I graduate. I will not get my BSN, just MSN and (hopefully) gain employment as a staff nurse, same as BSN graduate would, in position and pay.
The advantage is that you have the opportunity for more advanced postions which require a master's - after gaining experience. It prepares you with classes on advanced practice nursing, clinical nurse leadership, management courses, and even didactic time shadowing a nurse manager and assisting a unit with a specific problem by implementing EBP. In summary, I would call it nursing school with a pre-management/pre-NP emphasis.
In my case, I figured that I wanted to get my MSN anyway, so why not do it in one shot. And if I plan on getting a PhD, or DNP - I can just jump into it after some years at the bedside, without having to go back to school.
Hope that helps, let me know if you have any more questions!