From the conclusion:
NAT may be a good short term solution to the address depletion and scaling problems. This is because it requires very few changes and can be installed incrementally. NAT has several negative characteristics that make it inappropriate as a long term solution, and may make it inappropriate even as a short term solution. Only implementation and experimentation will determine its appropriateness.
It did, wherever it’s used. If you can ditch backwards compatibility in your network and just use ipv6, everything gets so much simpler.