I can highly recommend staying at Lu‘s apartment.
It has an unique view over Amsterdam - exactly as shown on the pictures. Service is overall great, Lu is a very supportive person and if you ask her she will help you to do your trip planning without missing any of Rotterdam‘s highlights.
City Center is less than 5 minutes walk away. There is a restaurant on the opposite side of the street which I can recommend as it offers quick and great breakfast.
Would definitely stay there again.