Pros
Excellent salary and benefits. Frequent open bar events and annual trip to a resort for a weekend. Good experience in dealing with the client for requirements analysis and testing.
Cons
Must be willing to move across the country with very little notice or be fired. At my current site there is very little team loyalty and the feeling of disposability of employees, although many other sites have a more positive work environment. You will often be over-worked, leading to a lack of work life balance. A large focus of the company events is alcohol. If you do not drink you will have trouble fitting in with others and it will limit your career. A large number of the tools you will be using are developed in-house and so learning to use them will not be a skill transferable to other future jobs in your career.