Pros
Projects were engaging, challenging, and directly relevant to the firm. By the end of the summer, intern projects were used by the traders. Expectations for performance are high, but everyone at the firm has personal standards that exceed those, creating an environment where each employee pushes themselves to surpass expectations. Many, many opportunities for personal and professional development, limited only by the intern's desire to pursue those opportunities.
Cons
Standard trading work hours; longer than most other jobs but on par with other trading hours. Internship is not regimented like some banks and other shops; it depends on what needs to be done and other factors. If you can handle a fast paced, changing environment, that won't be a problem. If you can't handle that, perhaps trading isn't for you after all. Conversely, most pressure comes from each individual employee on themselves. Anyone who relies on constant reminders and pressure to perform would likely not do well at OMC.