I admit (though a bit shamefully somehow) to enjoying "Hostel" (enough to buy a DVD), and even liking "Hostel 2" fairly well. This direct-to-video continuation, though, adds nothing to the story, only borrowing the idea and transplanting it to a new locale (Las Vegas), all the while missing the mark on gore, sexuality, and clever ideas. Eli Roth is no longer involved, either, so take that as you will.
Basically, after an initially playful and surprising opening scene (kudos to whoever was responsible for that), we get a rip-off of the first "Hostel" movies. A small group of young men are visiting Vegas for a bachelor party, where they mistakenly get involved in some seductive "party girls", who unwittingly get them all staked out as targets of the covert Elite Hunting Club, where privileged members get to place wagers on human lives.
While not an altogether awful film, "Hostel Part III" lacks any sort of edge or angle to build upon the first 2 films in the franchise. In short, it's a shallow and unnecessary cash-in. Avoid, unless you've got too much time on your hands and are attached to the first 2 "Hostel" flicks.