Re Comparing JS&MrN with Harry Potter - I haven't read the books but watched the first couple of films. HP is written for children and JS&MrN obviously isn't. This shows in a number of ways in HP, but especially in the pervading overall atmosphere of gaiety and flippant mischief, in direct opposition to the dark, foreboding, ominous feeling that is ever-present throughout JS&MrN.
Specifically, how magic is done is very different in HP and JS&MrN: In HP, it is just the uttering of the spell's Latin name. In JS&MrN, Jonathan Strange for example had to figure out the method through which the desired outcome could be reached during war.
And then, of course, you get to hear about all the consequences of magic in the footnotes, like when JS transports Brussels along with its inhabitants to America:
In 1830, a trader and trapper named Pearson Denby was travelling through the Plains country (in North America). He was approached by a Lakota chief of his acquaintance Man-afraid-of-the-Water who explained that in some nearby hills lived a tribe called the Half-Finished People. They had been created very suddenly one summer, but their Creator had only given them one of the skills men need to live: that of fighting. All other skills they lacked; they did not know how to hunt buffalo or antelope, how to tame horses or how to make houses for themselves. They could not even understand each other since their crazy Creator had given them four or five different languages.
Intrigued, Denby sought out the tribe of Half-Finished People. At first they seemed like any other tribe, but then Denby noticed that the older men had an oddly European look and some of them spoke English. Some of their customs were the same as the Lakota tribes’ but others seemed to be founded upon European military practice. Their language was like Lakota but contained a great many English, Dutch and German words.
"Crazy Creator". "Half-finished people". I love it 