I shadowed once a nuc. pharmacist so I can tell you a bit about. Salary wise I dunno why some people refer it as a lucrative branch of pharmacy coz an average salary is below what retail pharmacists make. The environment they work in I would describe as a lab.
Nuc. pharmacists have 3 shifts and the most important one is a night shift coz you have to prepare all these radioactive dyes for early morning, so if you'd start working there, they would definitely put you to work at night. Although in general all pharmacists rotate.
Now, exposure to radioactivity. They say it is safe, but the point is that you are getting certain amount of radiation anyway. So if you work there for 15 20 years - I don't know - I would say u'r still affected significantly. They all (pharmacists and techs) wear there rings on their fingers which show how much radiation you are getting. From time to time these rings are checked for radiation exposure and if you are over your limit (there is a certain limit) you are not allowed to work for a certain amount of time.
The job outlook, I would say, is very good.