Pros
Really took good care of their workers, and contractors were included in that. Safety is drilled into you at every level, inductions and training are at a high level. Multiple kitchens/great coffee machines/water on every floor. Good building locations within striking distance of good eateries for staff. Micro-breaks and quick exercise for office staff, you may laugh, (as I once did) but that stuff works. Upper management appear to walk the talk which is good, and their heart appears in the right place. Never forget they are a business though. Security audits, but not in the right areas while I was there... Career-wise I can't comment as a contractor only. They did offer FTE (Fixed-Term Employee contracts to their 'perms' of a couple of years which helps ensure performance).
Cons
As contractors, we were subjected to a high level of micro-management, but that was largely our org doing it. Stressful doesn't really describe it, miss a KPI, or make a minor mistake and it would be brought up in the weekly meeting for all to see. Demoralising. Not Chevron's fault really, but I wonder if they ever marvelled at our results, and wondered how we got those numbers. Contractors are subject to two sets of rules, those of their direct employer and the client also. Duplication of effort, wasted money on projects that never completed goals. I worked on a couple of projects, and witnessed unusual things that left me worried. Project managers were good, but constrained by management. Became, or had the potential to become very political, and stupid to the point Chevron was not getting any value, and losing good people, and prior work. Bringing change would require someone with large balls willing to risk their job, and few were willing... Mid-tier management were hit and miss, some were just excellent, some wouldn't even turn up to meetings they'd accepted, that were important (more than once!). So strange. Computer-based training, while excellent, was getting dated. A bit easy to work the system, some people eventually were asked to leave unfortunately. (Not me thankfully). People are warned about integrity, and undergo training. Were very top-heavy mid and upper management, but I hear they went through with a broom locally for many people.