Pros
There is a good amount of travel available especially if you are supporting long jobs. Good office/field work balance- you will stay in shape due to the nature of the job. Job security is a plus, once you are out of probation you can kick your feet up and coast your way to retirement.
Cons
It used to be a privilege to work as an On Site ‘designer’, but now there has been a greedy corporate influence that has been spreading from all the way back east. There is a constant trend where experienced hard working employees get the raw end of the stick while keeping lazy incompetent workers around because of “union stipulations”. You are pretty much invisible and have ZERO representation while paying union fees and getting no support. Managers and supervisors are only worried about their spreadsheets and forget the human aspect of there employees.