Pros
The variety of the projects was the primary draw to AECOM. If you could align yourself with interesting co-workers, there was the possibility of generating a good stream of project work. The benefits were middle of the road. The company does attract a lot of interesting people, though it has trouble keeping them.
Cons
The company is a disorganized mess because it tries to be everything to everyone. The size and revenue requirements of the company makes it such that they have to compete in a lot of commodity consulting, where price is the only real factor for clients. That leads to working on a lot of uninspiring projects. There is a lot of pressure to work off hours and off the books to make projects profitable. The culture suffers from the frenetic pace of work and the focus of profitability at all costs. And the profits go to management and shareholders, not employees to any measurable degree. A lot of talent has broken off from the company because it such an unwieldy clunker of an operation that underpays its people.