a) Bart Smaalders (with plenty of help from Glynn Foster and Shawn Walker) introduced IPS into Solaris
b) they did away with JumpStart(TM)
c) they did away with compressed Flash(TM) archives
d) they did away with sparse zones
e) Oracle closed the source code
I went to illumos / SmartOS and never looked back. I understand from a fellow engineer who still runs Oracle Solaris that 11.3 is the latest version, and I couldn't care less. I will never accept IPS because it has no preinstall / preremove / postinstall / postremove on purpose. Never, ever. I do my own builds of SmartOS from source code, PXE boot it from the network, and all is well with the world.