Pros
One of the best places to gain basic training. This is a company struggling to find an identity for the 21st century... which gives it tremendous potential (for either success or decline). Individual experience is dependent primarily on the quality of your immediate manager and their immediate superiors, as would be expected in any large (35,000+ employee) multinational firm trying to redefine itself.
Cons
The unique history of this (non-public) enterprise provided a most credible corporate foundation to build loyalty between the Johnson family and their employees. However, executive arrivals in the last two years were voluminous... accompanied by even more voluminous reports of executive departures... some of the brightest long-term Fidelity executives plotted their own exits to Putnam Investments and Morgan Stanley. Other long term Fidelity executives quietly and abruptly found themselves outside the evershrinking "circle of trust" atop the Fidelity pyramid, creating the largest leadership vacuum since the JFK tragedy in Dallas. The Fidelity workforce planners look outside the company to hire leaders, so it's unlikely that anyone with mid-level or senior-level leadership abilities and aspirations will reach their full potential through long-term employment and loyalty to the company.