The first few stories are a bit sluggish and focus too much on the fantastical beliefs of peasants from that period, but Viy, Ivan and his Aunt, the story of the 2 Ivans and the quarrel, the Nose, the Portrait, the Overcoat and Diary of a Madman are all exceptional (the rest are average or worse). The fact is that we find ultimately that witches were not supernatural and that this was metaphor to some degree--many believed it then however--and that the marketplace was filled with them, the daughters of wealthy land owners, a condemnation of the merchant class (he speaks of how the educated are forced to beg and steal from the wealthy to survive). Other witches in what seem to be the more supernatural tales are frequently shown as the sexually promiscuous.  

Indeed, the cops, city officials, and doctors in these tales often survive by taking a great many bribes, and Gogol shows frequent ire for Jews and other merchants who exploit others. 

I much preferred Dead Souls, but there is enough great stuff here--and much of it is social critique and history--to make it a worthy read.