I worked at CONCOR (Less than a year)
1. the staff is very friendly
2. the departments work well with each other.
1. Being a PSU it has it's own share of delay due to bureaucratic work.
I applied through other source. I interviewed at CONCOR (New Delhi).
it was a very detailed group discussion on very usual day to day topics. They were looking for clarity of thoughts, speaking/expressing ability, ability to take decisions, leadership qualities and your decision making process. the only issue was that G.D. and P.I. were held on separate days months apart.