Well, I read (or skimmed) all the stuff that wasn't already in the SRD, and I must say: This is a good supplement to Battle Century G, with my only major gripe being that in hindsight, the options for converting the rules to a fantasy setting can already be done with options already in the free BCG and BCZ SRDs (which then again, may be a feature, not a bug). The only exception is the Elemental System, which is very good for a Persona or Shin Megami Tensei-based game; anything with Mons', really. But where this supplement truly shines are the Faction Rules, three different sub-systems that make a living and breathing world around the PCs.
The optional Faction Rules allows you to simulate being part of a larger organization or building up one from scratch, the latter more than the former. With the ability to add NPCs to a growing cast of 'True Companions' and gain bonuses from them, as well as rules that allow the faction as a whole to act militarily, financially, and politically in the PCs' favor, the Faction Rules are lovely. Note that said rules do include a collateral damage sub-system (which I recommend for masochists or realists), and that might get in the way of builds that are built around blowing stuff up. But still, the image of a band of brothers/true companions/adoptive family forming around the PCs and slowly winning...that's a well-loved plot for a reason.
But what was truly a pleasant surprise is the 'Circumstances of War' mechanic, which allows you to personalize individual operations with maluses and bonuses and stuff that can be taken as both (extra Tension). This ensures that you no longer have to rely on just terrain and Mecha to make each battle different. That said, though, people have said that Pilot-scale combat is the worst-written part of the rules ever since Battle Century G itself, and it is such a shame that it requires a bit of custom work to apply these rules to battles that are not between Mecha. Nevertheless, one cannot have everything, especially in a supplement that is already solid.
[4 of 5 Stars!]