Pros
You are usually given enough time to get tasks done, and given proper tools to get them done. Performance appraisals are fair unless you are grossly incompetent. At times, the work itself can be interesting and challenging. You are given opportunities to become the key "go-to" person for key technologies. Opportunities for travel exist. These trips provide good opportunities to visit and spend time in foreign lands. As an employer, ASM is very fair to its employees. Many employees have left the company, only to return a few years later.
Cons
No job security to speak of. When manufacturers are investing in capital equipment, ASM hires like crazy. When equipment orders dry up, lots of folks get laid off.. From a software development point of view, there is very little opportunity for design and architecture. Most of the development is maintenance activities.