I was employed by Watson from 2006 to 2008 in the manufacturing end of the business. Employees on the floors were expected to wear full coveralls over regular clothing, steel toe shoes, hair nets and beard snoots for the guys with facial hair. Management and science/maintenance departments wore smocks instead of coveralls. Office attire, from brief interactions with personnel, seemed pretty casual, anything from jeans with a nicer shirt and sneakers to some of the ladies wearing low heels or flats with a skirt and blouse, pretty much depends on your job description and expected duties along with your personality, however absolutely no spaghetti strap tanks, flip-flops or loose, baggy clothing (the obvious fashion no-no's at pretty much any major corporation).
As far as the culture, Watson employs many, many people, across different buildings in a certain square mile radius, and given this, each building had its own culture of people. My building seemed a bit "cliquey" if you would call it that, most people were friendly and helpful but each shift has their own groups that hung out together. Not always a bad thing. I'm pretty sure once you get to know the people you work with, Friday night happy hours and get together's will come in its own time.
A typical day on the production floor involves a lot of patience,stress, documentation, cleaning, accuracy and verification.
Aside from a mass layoff in 2008 when I left, I actually miss working at Watson. I was a 3rd shift manufacturing support technician in building 1. Graveyard was pretty fun, now that I am thinking of it again. The environment is just awesome- to see the blenders and weighers in their space-suits..it's just a cool place to work.
Hope this information helps!! Good luck!