Pros
A career that you can start all the way from university (paid for). Will give you great opportunity as a graduate (you will have higher responsibility, much quicker than other industries), opportunity to live all over Australia and serve overseas. A great job, particularly straight out of school. Great salary and benefits. Once you're keen to move into civilian industry, opportunity to still serve through the Reserve.
Cons
Nothing that people don't know about when signing up to the military: you will be expected to move around a lot as well as serve overseas. Not really a con, part of the job, and when you want more stability, the option to serve in the Reserve is there. Technical engineering roles are usually contracted out, so those not interested in long-term management roles may feel like their skills are not being maintained.