Pros
Trayport is a successful and stable company, so you get job security. If you are a software developer, you get to work with mostly modern tools and frameworks. If you are in client management or support, you get exposure to a range of large companies such as investment banks and energy utilities, and the opportunity to travel throughout Europe. The office is in a good location, and is pleasant and well-appointed. There are plenty of enjoyable social events.
Cons
Trayport is a mature business which dominates its niche and faces little competition. As a result, there is a culture of stagnation and complacency. There are few ill consequences to missed project deadlines or unhappy customers. There is not much innovation and the pace is slow. I agree with the other poster who noted that a few of the managers are rude and unprofessional.