Pros
If you get placed at a big client site you get most of the good perks of working for the company (Better pay, better insurance deals and better hours). Free uniforms. Easy job usually. Good for work experience. The only reason I'd recommend this job to anybody is that it's really just a easy paycheck. If you can't find anything better than it's alright. Just make sure you don't let anything go wrong with the location you are working at and you can be employed until you die.
Cons
Expect late checks when you start and continue to expect them if direct deposit is not available. Expect to have your hours cut if it will save a little bit of money. Don't expect a promotion. Don't expect a pay increase (Unless the company some how gets a pay increase and even then it's probably no going to be passed on to you. Crappy uniforms and long wait times to get replacement uniforms. Backstabbing is almost encouraged. Unless you can find a group of people who will look after each other you will basically be on your own. Hard work is appreciated but not acknowledged (Don't put in extra effort if you don't have to as they will both get the same outcome). Expect to be talked down to and sometimes berated (Whether jokingly or intentionally).