I don't have any direct information on the NROTC Nurse option; however, if you have someone who is interested I highly, highly recommend they get in contact with a Nurse Corps junior officer and get some valuable insight into being a Navy Nurse. You want someone who is an ensign or a Lt(jg), by the time they have hit LT the vast majority of navy nurses are out of hospital floor nursing and have made their way into the more managerial positions.
There are some great training opportunities for Navy nurses though including the CRNA program, critical care, post-operative, and others but seems that the majority run from hospital floor care at the first opportunity.