My experience of Saudi is old - 1980. So things may be quite different now, so hopefully someone with more recent experience will be along. However, I think it all depends on the type of outfit you are going with. If it's a big organisation with a compound, it's own facilities, etc. then you may well find it comfortable. If, like me, you are with a relatively small company living "in town" you might find your "leisure time" a bit unfulfilling. I ended up working 6 days a week and lots of overtime just to make the time go by. It was sometimes a bit lonely though of course international communication is so much easier now. Back then it was airmail! At the end of a year I'd had enough. Mind you, my pockets were bulging when I came home. Some guys I knew working for the big oil companies had been there for years.
I don't know how relationships are these days between the Saudis and British expats. Back then it was OK, though some did like to rub our noses in the fact that the Middle East "problem" was all our fault. I don't know if particular issue has more prominence now. My gut feeling would be most Saudis don't give a stuff, they're doing nicely thank you.
Oh, where would you be going if you went? It's a big place. I was on the Gulf coast so at least I got to see water now and then. I wouldn't want to be based inland.
Whatever contract you go out on, ensure there is a reasonable notice period should you wish to jack.