Pros
Good salary, perks like free meals once a week and plenty of high-quality refreshments, attractive office, courteous coworkers (won't make a lot of noise to disturb you in the open floor plan), free parking within a block of the office--sometimes in the garage. Lots or opportunities to learn about CROs and the medical research study process.
Cons
Employees who are brought on overtime-exempt may be expected to work heavy overtime to get the job done instead of bringing in additional help--sometimes because they don't hire qualified people, so it's up to their successors or other employees to make up for it. Not a big company, so there may not be promotional opportunities depending on your department. Often best as a stepping-stone to positions with other companies in the industry (going into clinic/study management, etc.). Management doesn't plan well and sometimes hires the wrong people for certain positions--they talk big, but make a lot of mistakes, and the employees end up paying for it.