Pros
Huge company, when times are good there is a lot of opportunity to move around and money is flowing everywhere for an enjoyable workplace. Fly In Fly Out roster can be good for lifestyle, though a decision needs to be made for salary vs. length of time on site, and what sacrifice you are willing to make. Salaries are generally quite high though this is not expected to last.
Cons
When resource prices fall, so do many aspects of the job. This may just be in comparison to when times were great, but I'm inclined to think that there is a serious culture problem. There is very little job stability as the senior/management team are constantly rotating and the 'focus' of the team is shifting as a result. Many work friends have been made redundant around me, and there seems to be little reasoning to this as quite often poor workers are left while great staff are let go. Not a specific gripe with Rio Tinto, but as for a FIFO role in general - if you happen to change panels, you will go from spending 12 hour days for a week or two at a time with a work friend, to being on the opposite panel and literally never seeing them again due to the nature of the rosters being back to back. Personally I have found this to be draining over the years.