Ventajas
The working hours are good - 0800 to 1600 (Breakfast n Lunch breaks Included). The officers Quarters are a stone's throw away, Hence you needn't even buy a vehicle! There are so many verticals in ECIL. I will comment on the division I've worked in, Controls and Instrumentation division. As a young Engineer, you have to pack your luggage for all times because you have to tour all over India implementing Oil n Gas sector Automation projects. It gives us great exposure to places in North India. It is fun. You'll have free time in office hours, so you can learn anything you want! However, do not expect spoon feeding from seniors.
Desventajas
The salary is laughable for a PSU. The constant touring will take its toll once you are married at a young age. However, the tours will gradually stop as you climb the hierarchy. You will get calls from the project site even at 0300 in the morning!