Pros
In my long career in this industry, I've worked for a few of the competitors. CIGNA is one of the best. The senior leadership team is strong and drives the company message down throughout the workforce: through respect, example, and strong communication. The quality of employees is much higher than their competitors, so expectations of employees are high, however the environment is safe for employees to learn and grow without fear of being fired for one mistake (like some of their competitors.) Workload is large, given the state of our economy, but work/life balance is promoted and encouraged. Compensation is reasonable.
Cons
It is a large company, with layers and red tape, just like any other large company. CIGNA does a decent job of balancing innovation and creativity with checks and balances.