Some of the material was already published in Pyramid magazine but its a lot of new stuff as well, also nice to have it in one place. Rascally its a splat book for those delvers who are specialized at defeating Demons, Mages, or the Undead.
Each slayer type gets its own chapter with a template and a nice set of abilities to do take out their foes.
4 pages of demon slaying, most of the ideas are what a person familiar with GURPS would come up with but there are a few odd birds they are unlikely too.
Heroic Reserve has an unusual boost, several spell like abilities, and some of the other boosts are nice.
A lot of the same ideas in chapter 1 but with a different twist, and Magic Resistance gets a nice new modifier. As some of this material appeared elsewhere this offered little new to me, but not everyone has the magazines and other DF books these appeared in. Also there is new material here, and I like the format.
Also at 4 pages like the previous chapters this covers slaying undead and adds some new material.
The final chapter has some gear to support not just dedicated slayers but those going after the above type of foes. My highlight topic of the chapter was Talismans, but there is a nice set of items and ideas here.
A nice quick easy read that can add some interesting options to your DF campaign.
Blessed, Energy Reserve, and Magic Resistance all got a short but potentially very useful twist that can be used in a variety of settings, not just Dungeon Fantasy.
Definitely worth the $6 :)