These comments are purely my opinion based on my experiences and not statements of fact.
Management is absolutely toothless. I am astonished at how poorly the organization is managed.
For many managers it seems as if Experis is a place to land until they retire. There appears to be little desire to change what is known to be broken, to improve archaic, manual processes, or to invest in its people (I had zero training). It is all about what you can do for them.
There is very little advancement opportunity. Where you enter the organization is likely to be where you remain as long as you are employed there.
Work is not always steady nor are projects reliable. You will be aggressively recruited but do not expect the same level of enthusiasm or attention once you start with them. Be prepared for hard negotiations on your hourly rate. Their margins matter first and foremost. You can and will be replaced without notice if the client or Experis deems it appropriate.
Office politics in some locations is atrocious, mean, personal, and petty. There is a lot of finger pointing and bickering (especially behind each others' back). Turnover is very high, but it seems to be an accepted cost of business.