Join only if you are not finding job anywhere better.
Pros
They have huge number of projects across USA. So, if you join as a FTE, you kind of have a job security. If a project ends with one client, they can move you to a different client.
Cons
No work-life balance at all. You are expected to join calls at ungodly hours; 6-7 AM, 8-9 PM, weekends... If you suggest alternate time, you are "unprofessional". Since most other employees bow down and accept mandate from managers, the one who asks for logical timing becomes the sore thumb. Extremely manager-centric corporate culture. Managers behave like slave owners and implement a "my way or the highway" practice. Compensation is paltry. Every year they have "budget issue" when time comes for salary revision. Their appraisal process doesn't affect compensation. Even after getting highest class of rating in appraisal, you'll get "we'll see next year" when you ask for raise.