Pros
Great benefits -- the health insurance offered is very good and low cost to employees. The people who work for ICON are smart and very hard working. You'll make some great connections for future job opportunities (because the turnover at ICON is very high).
Cons
Employees are over-allocated, underpaid, and under appreciated. If you enjoy working your ass off, working long hours, and struggling to meet timelines because of a lack of resources, only to have it go unnoticed, then ICON is the place for you. There is no career development here, unless you know how to work the system or are lucky and assigned to studies where you are given opportunities. It's hard working in the same position for years with no guarantee that you'll ever get anywhere.