Don,
I'm English but living in Turkey. I spent 15 years with the old (Qatar General Petroleum Corporation...now QP and that covers the entire oil/gas sector) and yes there are ups and downs.
Social provisions (Company facilities) have deteriorated over the years but the developments in Qatar have probably made up for that. Another plus is that the country is now far more tolerant of Western behaviour and habits.
Be warned about the housing costs. QP at one time provided free housing and utilities (including phone line rental). They then applied a limit to electricity and water useage after which you pay and I'm not sure if they pay for the phone line now (unless it's required for the job).
If housing is provided I suggest that you take it. You will see from other posts how the cost of housing has risen.
Ask QP all the questions to which you require answers.
Whatever you decide to do.......... good luck.