My initial thoughts on the class are pretty similar to the general consensus: Really low skill points for a Ranger/Rogue mix. I'll agree that Bluff is an absolute must, but Disable Device less so.
When I'm thinking the flavor of this class, my mind immediately conjures up the Wetboy as presented in the Night Angels. A methodical killer who isn't an assassin, someone who plans out an execution and leaves little evidence. Assassins leave ancillary casualties when they try to escape.
That being said, I think expanding the list of talents available to the Slayer (especially including Ninja Tricks or Rogue Talents as Advanced Talents) would be a solid way to go, after bumping skill points up to at least match the Ranger.
Of all the hybrids I've gotten a chance to look at, this is one of two that I'm actually jonesing to play.