Book introduces unparalleled level of complexity to even simplest actions. If you are familiar with your GM's Section/Book for your chosen system, most of tables here will not be necessary and will slow down your game. Rules adjustments are focused on changing d20 game mechanic to be less or more difficult for solo play, again if you know your system you won't need it. I like simplified FlexAI rules, might be handy for this one fight where you want your adversary to act in unpredictable way - note that there is free version of this engine if you like to try. If you are seeking inspiring prompts for your adventures, help in creating conflict for your character/s to face - try other sources, you will find no such content here. If you like to have random dungeon challenge, with good map generator and adjusted to your favorite system then this book is worth checking.
Update after Creator Reply:
My review is written from perspective of solo player which seems to make most sense for title like this. While you may have different approaches to a game like this, the goal is to build compelling narrative that gives you interesting choices, letting you experience their consequences as well as track your progress. By far the biggest challenge is to be surprised by events you are taking part in. Having the plot outlined - like in Solo Quests section or published module - can work if strong element of uncertainty will be introduced. In this book you can find mechanic to track progress and some random encounters that does not change plot/scenario structure. Having said that, I think this book contains some very good tools for non-Solo GM when it comes to building scenarios.
Regarding Rewards and Penalties sections, rules takes ~86 pages and more then 120 tables to answer question "What do I get from this quest?". To be honest, in rpg you can always have rule for anything and it can be as complex as you like. Will it help you to generate unexpected results? Yes, however at cost of momentum and this is really precious commodity when playing rpg solo.
[3 of 5 Stars!]