Kett doesn't care about their employees. They work with big name clients and like to keep a string hanging in front of you like you're a donkey to lure you into thinking you'll become an FTE at the client company but from what I've seen from previous employees, it takes more than 4 years to do that, all while paying you a meager wage that can't keep up with inflation.
Good luck finding any opportunities for advancement. You can do all the work you want for the client, produce enough output, submit your work perfectly while meeting deadlines, but if you don't do it their way or their client is somehow not satisfied, then you're a failed employee in their eyes. Kett and the clients they work with want to milk every drop out of you while you slave away for them.
If you need a job simply to pay for rent/bills/groceries, then it's a (laughably) decent option. Keep your expectations to an absolute minimum, don't appear to management as an overachieving "go-getter", learn how to game the system, and you'll be good.