Pros
Amazing exposure to a huge variety of test equipment, methods of testing/calibrating, and customers' facilities of many different industries. Pay is decent, overtime is almost always available/required.
Cons
Ridiculously understaffed, underfunded, and overworked. Training and proper preparation for any onsite work is a luxury that can almost never be afforded. All problems are addressed retroactively, even if potential solutions are identified beforehand. Standards are old, obsolete, poorly maintained, and in most cases in worse shape than the customer's equipment. Vehicles were always in terrible condition. Technicians are required to make the company a certain amount of money per hour ($135 when I left), and are threatened with write ups, lack of annual COLA raises, and termination for failing to meet the quotas. The quotas are insanely unrealistic, leaving technicians with no other option than bullshitting the vast majority of their work in order to make their dollars per hour, or quit. Consequently, most of the people who stay with the company long enough to be promoted have zero integrity when it comes to calibration and silently expect you to follow suit. PTO is forfeited after submitting a letter of resignation. You are not paid for any unused PTO. You are forced to have an hour lunch on your time card every day, even if you weren't given an opportunity to take a lunch because of their ridiculous op-tempo. Ten/fifteen minute breaks are rare. They expect you to be able to calibrate every T&ME ever created with a handheld meter and a paper clip, with no training, on-site, calculate measurement uncertainties for every test point, conduct all of the required research for the calibration, and complete all of the associated paperwork in about a third of the time that it should take a competent, hard working technician to do the job adequately.