I am a gadgeteer at heart, and always played that sort in most kinds of games. Thus, while I am the GM in my current homebrew, and haven't had the chance to play in many years, my favorite regular party NPC is an artificer. This said, number one favorite thing is augment crystals. They are too cool.
Second, as already mentioned, the arcane version of traditionally psionic items.
Third, the new format. Still a bit padded (ummm ok so desription of flaming feature is a weapon on fire...DUH), but not anything that really eats up the page count, and the listing is REALLY simple and self explanatory.
Fourth is the gathering of the various weapon and armor abilities not found in the DMG in one place. Combine this with Bastion's Arms & Armor, and you are really good to go.
Fifth is the synergy abilities. I have always thought that the burst capability should be it's own listing, seperate from the energy it is based on. Now it is. Plus, they add a few new synergy abilities to some of the old standard, like the already mentioned ghost touch. All of this is especially useful in my homebrew, as I have technomagical devices that basically use a combination of perpetrated press's Arsenal and Factory, combined with Iron Kingdoms mechanika item creation rules.
It if says anything, I even paid FULL price for this book, which I almost never do, to get it last friday rather than wait a week or two and order it online. That said, I still feel like I got my monies worth.
skippy
The GM of The Cursed Earth Campaign