Pros
There are some quality people, good managers who want to provide value for their clients. It can be fun exciting work. Some environments require working with people that may not be co-located. Up until 2011 the overall environment was good and job seemed stable. Despite the uncertainty in some of ManTech's sectors, ManTech provides opportunities to try to retain and reassign employees to meaningful assignments.
Cons
Unfortunately a lot of the experience is dependent on whom you end up working under. Compensation in West Virginia seems to be behind the curve of nearby areas. Lack of co-location should not be a huge factor in any team culture, but it requires effort on the part of the team leader to ensure all of the team feels a part.