The new edition is the result of eight years of feedback and battle reports from players, as well as the evolution and improvement of the core rules through our other books Daisho, Blood Eagle and Thud & Blunder.
A full description of the changes can be found here:
https://theministryofgentlemanlywarfare.wordpress.com/in-her-majestys-name/. Just scroll down to the downloads and open the second one called: key-changes-between-ihmn-and-ihmn2-v1
The original rules were a 25,000 word, 64 page book, and were our first published work. IHMN2 is 85,000 words and 196 pages. It contains all the key information from the original, and a whole lot more.
It still has a completely open points system and there is guidance on how to create your own themed companies, as well as how to cost equipment, talents and mystical powers.
The campaign rules can call upon the scenario system, which can generate over nine thousand unique games.
Many of the companies from the original books have been carried over, but not all. Our intention is to release a series of thematically-based digital supplements covering different parts of the globe, and beyond.
IHMN Gothic is being maintained and further down that list of downloads is a free supplement showing how to use Gothic with the IHMN2 rules.
I hope that answers your question
Feel free to ask more.