I've been working in KSA for a few months now, and honestly I disagree with everything, that's been said here. Problems with visa, passport, money...?! Nobody was trying to withhold my passport, I got it back along with my residence card and multiple entry visa. I am being paid on time. Money is decent. I have really good accommodation, that I don't need to pay for. There are guys who came here together with wives. People extend their contracts and don't even plan on going home or anywhere else. Working conditions are really good.
I have worked in China before and even though I did enjoy it generally, maybe mostly because I liked the place, KSA - as far as working conditions are concerned - is such a better choice.