Pros
Most of the time they will answer the phone and sometimes they will return your call from voicemail. They have free online training video courses. They will come around about once per month and take all of their employees out to lunch. At least you get some work.
Cons
Absolutely no benefits. Offers go to their favorites first regardless of their qualifications. They will ALWAYS offer you lower than other companies recruiting for the same position. They keep secret the actual client's name until you commit with them to avoid competition whereas other companies will clearly tell you. For example, I was submitted for a position by one company and offered $25 per hour. The next day TEKsystems calls me about a job with the same description and confirmed that it was the same client. "I will try and see if I can get you $15." No thanks. I will take the exact same job with the other company at $25. Their recuiters are always getting company paid benefit trips to Cancun and such as bonuses for all of the money that they saved the company with their low-ball tactics. Their online video courses can only be accessed with an older XP machine which has not had IE or flash player upgraded.