Pros
You can work on some high profile jobs if you are well connected enough within the company. Benefits are better than most companies.
Cons
No respect for work life balance. If you are salaried and non billable expect to work 60-80 hours a week to make up for the overtime the non salaried people are not allowed to put in as AECOM is squeezing everything they can out of their employees. If you are billable and your utilization is not above 90% you will not last long. All non-billable paperwork must be completed on your own time pro bono. Too many levels of management to get anything approved. AECOM has kept all the management from the operating companies that they forced together. This has lead to a multilayered labyrinth of no one knowing who can do what. There will be a mass exodus come December 15th when lack of salary increases and new titles are announced. This will be the final straw for most.