The Norwegian Public Roads Administration is using the protocol OPC-UA in an IoT project for gathering and analysis of road traffic data. OPC-UA, while not very widely used, fits our needs very well, and has some valuable properties that might fit other IoT projects in other domains. We have been using the protocol for more than 2 years in our project. In this talk, a short introduction to the protocol and its abilities will be given, along with a feature comparison to alternative protocols. Then, a walkthrough of the experiences we have had during the project - from initial design concerns behind the protocol choice, to a wide selection of surprises and obstacles when starting up - and finally how we reached an end state of a stable production system. The presentation will end with a summary of hindsights and some suggestions for selection criteria when considering protocols in IoT projects.