Pros
I've served many years at Framatome (formerly AREVA) and it is without a doubt a great place to work. If you are skilled and ambitious you will have plenty of opportunities to be challenged with interesting problems that you can solve alongside some of the brightest minds in the industry. That said, there is often a lot of people that you may be forced to work with who have no problem "phoning it in". This is surely a testament to the amount of job security you will have at this company, but can be a detriment to your morale if you let it. Take more note of the positive experiences you have at this company and the experts you get to work with and regardless of your career path you will come out on top.
Cons
There are many employees who seem to just "phone it in" and they are allowed to continue this practice without management intervention. Surely, this is an attribute of any large organization, but there seems to be no be no action from management to address this issue.