The evaluation by an independent team of researchers of the Norwegian legislation that prohibits the purchase of a sexual service is now available. As was the case with the evaluation of the Swedish legislation in 2010, the evaluators conclude the following:
1. The ban on purchasing a sexual service has reduced demand for sex and thus contributes to reduce the extent of prostitution in Norway.
2. The enforcement of the law, in combination with the laws against human trafficking and pimping, makes Norway a less attractive country for prostitution-based trafficking than what would have been the case if the law had not been adopted.
3. Furthermore, the economic conditions for prostitution in Norway are reduced following the implementation of the law.
4. These effects are in line with the intentions of the law and are, thus, not considered as unintended side effects.
5. This report does not find any evidence of more violence against persons in prostitution after the ban on buying a sexual service entered into force.

You can find the evaluation report here.
The lead researcher gave a short interview on Norwegian television here.