Pros:
What a unique and well-polished addition to the game! Right off the bat we have essential gear that makes everything better (Grappling Hook! Flamethrower! Scoped Crossbow! Standards that remain standards because they OOZE flavor).
We keep the abstract nature of Slayers in "Scrip", a handwaved currency. We have rules for next-of-kin, which I just adore so thoroughly. It reinforces the idea that you are dangerous folks doing dangerous things.
We maintain a sense of balance and simplicity by restricting 1 gear to each Slayer and having maintenance costs. The gear itself is fun, useful, and somehow dripping with even more flavor and cool factor than the base items themselves.
I should also mention that this product is cleanly laid out, with an original color scheme and style that is reminiscent of Slayers while still being its own thing. Everything is easy to read and elegant.
Cons:
There are a couple minor typos, and it's a little odd to me that I have to pay 1 scrip to remove my Book of Prayers, but that's an extremely minor quibble on an otherwise excellent product.
Summary:
This is an excellent supplement for Slayers that adds a unique layer of tactical combat, as well as powerful flexibility for Slayers. It allows for rewards, instead of handwaving currency like the base game, and is extremely flavorful while it does it! This is absolutely worth the asking price for any Slayers fan.