Amgen worker productivity seems to be diminished, and its culture appears to be conditioned by constant large-scale initiatives driven top-down. Teams' ability to execute is impacted by a culture of job-protectiveness, and even excellent and essential ideas are delayed for years waiting for various reorganizations. In a nutshell, Amgen does not foster ideation, invention, creativity; further, the company seems to reward passive-aggressive behavior.
Amgen's headquarters are isolated in Ventura County, CA, and while the benefits are great, I do not recommend relocating simply for Amgen. It frequently pays relocation benefits to new hires, but moving here could geographically block enriching opportunities from coming to you.
Good benefits, lovely campus, cheap cafeteria
Culture and ability to execute