All my comments and cons are based on my experience in RR Bangalore. I have little knowledge of the other divisions of RR.
1) No scope for career developement : I have seen people with 10 years of experince, people who were working as managers of entire department in their previous companies, working as a beginner in Rolls-Royce.
2) Your skills will be underutilized in RR. Trust me, this company is the sink of all your experience and knowledge. Tread carefully!!!
3) The Indian working culture: people here promotes hypocrisy and politics. I have seen people doing the most simplest tasks in excel or word and showcasing it to others as a great achievement. The worst part is that, others acknowledge it as something great indeed.
4) Stingy: Trust me, the name does not justify the pay they give.
5) paperwork: RRB has too much unnecessary paperworks and extremely prejudiced work culture.
6) White people are gods: whatever white people tell from UK is among the ten commandments!!!