Pros
It was rewarding to work at such a cutting-edge hi-tech manufacturer, with colleagues from all over the world. The flexitime was good, the pay excellent and management were generally approachable. However...
Cons
...the sheer size of the place meant there was a (perhaps unavoidable) high level of bureaucracy and what seemed like excessive organizational complexity. I often found that I was spending more time thinking about who I was supposed to be talking to or meeting with next, which section of the company and physical part of the premises they worked in and how I was meant to interact with them than I spent thinking about the problems I was meant to be solving. There were additional problems in terms of getting paid for employees like me who were technically 'employed' by an agency (and paid via a third company!) and not directly by ASML.