You should really buy Transmechs first
I took a break from juggling between Fantasy Craft and WoF (those books are so awesome I want to read them both simultaneously) to take a closer look at Transmechs, which I bought a while back.
I remember thinking it was pretty neat, but unfortunately, I have to reassess my analysis now; It's FREAKIN' AWESOME!!!
No, really, it gotted tipped into the pot of awesome sauce as a kid and ate it all up -kind of awesome. I could go over the way each individual mechanic is handled, but I'd just wind up repeating the 25 pages of it, when I could be spending my time more creatively, like by drooling and rereading it.
But individual stuff like pulling out Lifestyle and replacing it with the Spark... GENIUS.
I'm in a major situation now, I now have 4+1 different campaigns I really REALLY want to run (straight-up Agent Spycraft, Transmechy Spycraft, Time of Troubles Fantasycraft, Dragonlance Pathfinder as well as exploring the possibilities Spycraft gives for PnP Mass Effect...) What's a guy to do!?

Brilliant work guys, even in a range of amazingly cool products, this manages to stand out. And I'm a casual Transformers fan, at best.