I have travelled extensively in China (been to all provinces, and lived there for 3 years), and can say without a doubt that Nanchang (possibly twinned with Zhengzhou) was the worst place I ever visited. I can't think of any redeeming features, although as it was a long time ago (maybe 2008?) I can't think why is was so awful. Anyway, it was bad enough for me to have it on the "never again" list (and it's a very short list!). I quite liked Lushan and Jiujiang in the north of the province though.