Does this ability (Up Close and Deadly) work against everything that a regular attack would hit? Or does it act like a sneak attack/critical and things like oozes, most undead, ect. are unaffected.
It's Precision damage, and so doesn't work on things Sneak Attack wouldn't work on, but that's really few things in Pathfinder. Oozes and Elementals are actually about it.
Undead are very much sneak-attackable in Pathfinder, for example.
And the half-damage on a miss part would still work even on that kind of stuff.