Pros
CA's flagship software on the mainframe platform has been business-critical in many industries for several decades. It's not uncommon to find mainframe teams that have invested 25+ years in their product; the senior architects/developers on these teams are always very talented engineers, and have a sense of community that's quite rewarding to participate in .
Cons
The enterprise software division has been failing-to-thrive for a long time, while the mainframe BU remains a free cash flow machine. So upper management (hungry for growth and higher share prices) have continually diverted resources from the latter to invest in the former. It's unclear if (or when) this strategy will produce sustainable growth in enterprise. But it's very clear the continually-malnourished mainframe BU is an increasingly fragile situation. Each retiring senior architect leaves a productivity vacuum that the firm cannot fill even by ramping up recruitment in the mid-level talent pool it has access to.