Pros
The level of technical knowledge gained on the job is phenomenal compared to other similar jobs. High level of access to systems and servers provided unparalleled opportunities to learn and grow for those motivated to do so, and upward career movement was very possible once those skill sets were exercised. Each tech was basically a systems administrator in the making.
Cons
Policies were making all the pros above less and less effective. New products and services moved a highly trained technical staff into roles that were mundane and more typical of support situations, which in turn downplayed those skills, and in turn took away access and many opportunities to learn and grow. In the end, those skilled techs who stayed turned into glorified customer service reps.