So after fully completing the series this was my favorite in the series. After a hard climb from unknown our group beat the army's of a tyrant wizard king. There were some close calls but we did it. The last two scenarios ended very nicely with the last one changing up some rules that made it fun to play. This one made me really look forward to S&S more then I had before.
I have bought all of the Monster Focus by Minotaur Games so far and by far this is my favorite (and thats not just because I love liches.)
In this book you will find new alchemical items, spells, and magic items meant to help and to hinder these undead masterminds. Along with that there is a few new templates that can be added to the lich. Ultimately if you are planning on running your players against a Lich I suggest getting this so that you can have a few surprises up your sleeve.