Don't think he should be written off.
There is a wider concern though that players coming from the Dutch league are used to a different style of football than we have in the SPL. There game is slower, they look for more time on the ball and expect to be given it. This doesn't mean that they will not be able to adapt, clearly there are several examples of excellent players who have managed it but there are many who have not. Particularly at the lower end of the scale where we have seen the likes of JDV or Touzani, who were clearly technically competent players but really struggled to make a major impact.
This guy could be exceptional for Aberdeen but he may struggle, evidence so far would suggest that he will struggle. For me, he looks like a £9 bottle that might have been kept at the wrong temperature