I have found when doing my research that Rotterdam often gets poor write ups in guidebooks. I feel this is unfair.
Amsterdam it is not. It is a very modern city, due to being bombed to oblivion in May 1940. The result is a planned city centre, lots of very modern architecture, good nightlife and a fairly young population.
However, it does not mean that Rotterdam lacks an identity of its own as it is so young. Its moderness and youthfulness is its identity. It is an attractive city, though not in the sense of medieval streets. It is open and spacious, easy to get around and it has excellent public transport.
I would recommend it if you want to see more of the Netherlands than the traditional images of canals and windmills (there are windmills and canals close by if you need a fix).