We use iOS on various range of Cisco switches, mostly on the Datacenter and IT networks. It supports our L2 and L3 networking requirements such as switching and routing protocols. It helps connect users and customers spread out in various branches end to end and manages packet flow between server-client.
Well suited for building management networks across the organization as it has been reliable without much downtime. Since it has great switching qualities, it suites well for data center and end-user connectivity using access switches. It might not be the best for routing, as other XOR software has proven to be superior for routing.
We have found other Cisco software to be filled with added functionalities as compared to iOS. New NCS software has certain programmability features that are advantageous to legacy iOS software but are more complex to use for some users. Hence, we still have most areas of the network that functions using iOS software.