Pros
Every hour of extraordinary work is paid.
There is a very friendly and good atmosphere between co-workers and management.
Money when traveling is good.
Work can be very rewarding at times.
Travelling can get you across continents, and to interesting places.
Options for career shift within the company exist.
Kontras
Workload is fluctuating, you might have minimal work or you might have loads of work.
Onsite can be very very stressing.
There is no work life balance when on site.
It is not easy to preserve a healthy life when on site, possible but hard.
There is often a lack of organisation in projects.
Experience is very company specific and not easily translated into other industries.